The ubiquitination process is vital to maintain the protein homeostasis in the cell. With high specificity it regulates degradation of proteins by tagging them with a small protein called ubiquitin. Four proteins are involved to perform the process and in this thesis one of these proteins is studied. This protein is called Ro52 and belongs to the TRIM protein family. It posses E3 ligase activity because of a N-terminal RING-domain and therefore it is responsible for the last step in the ubiquitination process. The structure of Ro52 is not totally solved and the function of the protein’s four domains is not fully understood. In this thesis three constructs of two domains from Ro52 (RING and B-box) is investigated by circular dichroism (CD), nuclear magnetic resonance (NMR) spectroscopy and auto-ubiquitination assay by Western blot. The goal was to gain deeper insight in structural and functional properties of these domains. In the end only two constructs were investigated because of time limitations. It was shown by NMR that one construct has similar structure as the wild type but lower stability, possibly due to shorter N-terminal region. Comparison of the results from CD measurements showed that the constructs were well structured but did not reveal any significant differences in secondary structure between the constructs. Functional analysis by Western blot encountered unexpected problems and no results were obtained. The current thesis provides a basis for further investigation of variant constructs jointly expressing the RING-B-box domains, and shows that even small changes may alter structure and stability in ways that might affect functional properties.

The spindle assembly checkpoint (SAC) is an evolutionarily conserved mechanism that delays the initiation of anaphase by inhibiting the Anaphase Promoting Complex (APC) until all kinetochores have achieved bipolar attachment on the mitotic spindle. Mad1-3, Bub1, and Bub3, components of the SAC, are conserved from yeast to humans. These proteins localize to unattached kinetochores, though it is unknown with which kinetochore proteins they interact and how these interactions transduce information about microtubule attachement. Here, purification of the checkpoint proteins from Saccharomyces cerevisiae suggests that Mad1 interacts with the outer kinetochore protein Ndc80 in a SAC, cell cycle, and DNA dependent manner. Ndc80 is thought to mediate attachment of kinetochores to microtubules so the interaction between Mad1 and Ndc80 suggests a mechanism by which cells sense kinetochore-microtubule attachment. The SAC is of special importance in some types of cancer where genetic damage and aneuploidy is correlated with mutated SAC genes. A better understanding of the SAC mechanism will aid in the development of targetted cancer therpeutics.

Downstream purification often represents the most cost-intensive step in the manufacturing of recombinant proteins. Conventional purification processes are lengthy, technically complicated, product specific and time-consuming. To address this issue, herein we develop a one step purification system that due to the nature of the non-selective secretion system and the versatility of ion-exchange membrane chromatography can be widely applied to the production of many recombinant proteins. This was achieved through the integration of the intrinsically coupled upstream, midstream and downstream processes, a connection that is rarely exploited. A bioprocess for effective production and purification of penicillin G acylase (PAC) was developed. PAC was overexpressed in a genetically engineered Escherichia coli strain, secreted into the cultivation medium, harvested, and purified in a single step by anion-exchange chromatography. The cultivation medium developed had a sufficiently low conductivity to allow direct application of the extracellular fraction to the anion-exchange chromatography medium while providing all of the required nutrients for sustaining cell growth and PAC overexpression. It was contrived with the purposes of (i) providing sufficient osmolarity and buffering capacity, (ii) minimizing ionic species to facilitate the binding of extracellular proteins to anion-exchange medium, and (iii) enhancing PAC expression level and secretion efficiency. Employing this medium recipe the specific PAC activity reached a high level of 487 U/L/OD600, with more than 90% was localized in the extracellular medium. Both, the osmotic pressure and induction conditions were found to be critical for optimal culture performance. Furthermore, formation of inclusion bodies associated with PAC overexpression tended to arrest cell growth, leading to potential cell lysis. iv At harvest, the whole non-clarified culture broth was applied directly to a tangential flow filtration anion-exchange membrane chromatography system. One-step purification of recombinant PAC was achieved based on the dual nature of membrane chromatography (i.e. microfiltration-sized pores and anion-exchange chemistry). Due to their size, cells remained in the retentate while the extracellular medium penetrated the membrane. Most contaminate proteins were captured by the anion-exchange membrane, whereas the purified PAC was collected in the filtrate. The batch time for both cultivation and purification was less than 24 h and recombinant PAC with high purity (19 U/mg), process yield (74%), and productivity (41 mg/L) was obtained.

White wine clarity is essential, but it can be marred by the presence of a protein haze. This protein haze is predominantly formed by grape-derived thaumatin-like proteins and chitinases, which can slowly denature and aggregate if left in bottled wines. Currently bentonite fining is used by the wine industry to prevent protein haze. Bentonite consists of fine clay particles that, when added to wine, bind and remove the haze-forming proteins. However this method is inconvenient, time-consuming, and causes significant losses of wine. It is estimated that this process costs the Australian wine industry $50 m annually in wine losses alone. Alternatives are thus being investigated. The principal objective of this thesis was to investigate the sensory effects on wine of an alternative method to bentonite fining: addition of haze protective factor 2, known as Hpf2. Hpf2 is a Saccharomyces cerevisiae mannoprotein that has been shown to reduce protein haze in wines. It is a highly mannosylated 180 kDa protein, of which approximately 75% by weight is mannose. Previous work has shown that the addition of approximately 200 mg L⁻¹ Hpf2 to wines reduces the visible haze in wine by approximately 50%. Hpf2 is naturally present in wines at concentrations of less than 10 ng L⁻¹, much lower than the concentration required for haze protection activity. However, the sensory impacts involved with the addition of such high concentrations of Hpf2 in wine have never been studied. This knowledge is essential for the future commercial prospects of this alternative approach to protein stabilisation of wine. To undertake sensory studies, over 1 g of Hpf2 would be required. Presently, the laboratory-scale process for the production of a 6-histidine tagged version of the protein, 6xHisHpf2, in a laboratory yeast strain of S. cerevisiae, produces only milligram quantities. Consequently, the first challenge of this research was to scale up the existing process to produce sufficient quantities of Hpf2. The first attempt to increase the production level was by over-expression in the bacteria Escherichia coli. Although several approaches were trialled, 6xHisHpf2 was unable to be successfully and consistently expressed in this system. The second method was by improving the original yeast expression system, and the expression level was able to be improved approximately 10-fold. This improved expression method was scaled up to produce and then purify over 1 g of protein. Several quantification methods were assessed to determine the efficiencies of each purification step, with slot blot analysis proving successful. Sensory trials were conducted to establish the effect of 6xHisHpf2 on wines, with duo-trio studies conducted assessing both aroma and palate of the wines. Invertase, another yeast haze protective factor, was also trialled. It was found that the addition of an active level of 6xHisHpf2 or invertase did not cause a significant difference in the aroma or palate of wines. In addition to this main study, the role of the glycosylation was studied. 6xHisHpf2, produced in a different yeast, Pichia pastoris, was found to be 83 kDa, with only 50% mannose. This protein was compared to the S. cerevisiae protein in its ability to reduce protein haze, and it was shown that the P. pastoris protein could reduce haze, but not as effectively as the S. cerevisiae protein. The finding that Hpf2 does not affect the sensory properties of wine is essential if Hpf2 is to be used commercially, as winemakers and wine consumers would most likely reject an additive that alters the wine aroma or palate. This work has brought the wine industry a step closer to a new method for protein haze prevention in white wines. / Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, 2008

White wine clarity is essential, but it can be marred by the presence of a protein haze. This protein haze is predominantly formed by grape-derived thaumatin-like proteins and chitinases, which can slowly denature and aggregate if left in bottled wines. Currently bentonite fining is used by the wine industry to prevent protein haze. Bentonite consists of fine clay particles that, when added to wine, bind and remove the haze-forming proteins. However this method is inconvenient, time-consuming, and causes significant losses of wine. It is estimated that this process costs the Australian wine industry $50 m annually in wine losses alone. Alternatives are thus being investigated. The principal objective of this thesis was to investigate the sensory effects on wine of an alternative method to bentonite fining: addition of haze protective factor 2, known as Hpf2. Hpf2 is a Saccharomyces cerevisiae mannoprotein that has been shown to reduce protein haze in wines. It is a highly mannosylated 180 kDa protein, of which approximately 75% by weight is mannose. Previous work has shown that the addition of approximately 200 mg L⁻¹ Hpf2 to wines reduces the visible haze in wine by approximately 50%. Hpf2 is naturally present in wines at concentrations of less than 10 ng L⁻¹, much lower than the concentration required for haze protection activity. However, the sensory impacts involved with the addition of such high concentrations of Hpf2 in wine have never been studied. This knowledge is essential for the future commercial prospects of this alternative approach to protein stabilisation of wine. To undertake sensory studies, over 1 g of Hpf2 would be required. Presently, the laboratory-scale process for the production of a 6-histidine tagged version of the protein, 6xHisHpf2, in a laboratory yeast strain of S. cerevisiae, produces only milligram quantities. Consequently, the first challenge of this research was to scale up the existing process to produce sufficient quantities of Hpf2. The first attempt to increase the production level was by over-expression in the bacteria Escherichia coli. Although several approaches were trialled, 6xHisHpf2 was unable to be successfully and consistently expressed in this system. The second method was by improving the original yeast expression system, and the expression level was able to be improved approximately 10-fold. This improved expression method was scaled up to produce and then purify over 1 g of protein. Several quantification methods were assessed to determine the efficiencies of each purification step, with slot blot analysis proving successful. Sensory trials were conducted to establish the effect of 6xHisHpf2 on wines, with duo-trio studies conducted assessing both aroma and palate of the wines. Invertase, another yeast haze protective factor, was also trialled. It was found that the addition of an active level of 6xHisHpf2 or invertase did not cause a significant difference in the aroma or palate of wines. In addition to this main study, the role of the glycosylation was studied. 6xHisHpf2, produced in a different yeast, Pichia pastoris, was found to be 83 kDa, with only 50% mannose. This protein was compared to the S. cerevisiae protein in its ability to reduce protein haze, and it was shown that the P. pastoris protein could reduce haze, but not as effectively as the S. cerevisiae protein. The finding that Hpf2 does not affect the sensory properties of wine is essential if Hpf2 is to be used commercially, as winemakers and wine consumers would most likely reject an additive that alters the wine aroma or palate. This work has brought the wine industry a step closer to a new method for protein haze prevention in white wines. / Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, 2008

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: During wine fermentation, yeasts release extracellular enzymes that significantly impact wine properties. While the extracellular proteins of Saccharomyces cerevisiae have been characterised, those of non-Saccharomyces yeasts remain largely unknown. Most of these enzymes break down sugar polymers or catalyse the liberation of glycosidically-bound molecules. Another category of enzymes of oenological interest is represented by acid proteases that are able to prevent or reduce protein haze, as reported in literature, while simultaneously increasing the assimilable nitrogen content of wine. The liberation of amino acids from peptides and proteins that serve as aroma precursors may also have an indirect effect on wine aroma. In a recent study performed at the Institute for Wine Biotechnology (IWBT), the sequences of two aspartic proteases were retrieved from non-Saccharomyces yeast species isolated from South African wines. The genes, MpAPr1 and CaAPr1, were isolated from two non-Saccharomyces species, Metschnikowia pulcherrima IWBT Y1123 and Candida apicola IWBT Y1384, respectively. However, no further characterization was undertaken. This study aimed to clone these two genes into a recombinant bacterial host for expression and purify the corresponding enzymes as a first step toward characterizing their kinetic properties. Considering that some non-Saccharomyces species have been shown to produce more than one acid protease, an additional aim was to identify novel acid proteases within M. pulcherrima IWBT Y1123. Cloning of the genes and transformation of the expression vectors into E. coli were achieved. Optimal conditions for induced expression were established following extensive optimization. Furthermore, while native extraction of the recombinant proteins was unsuccessful, denaturing conditions allowed their recovery, suggesting that the recombinant proteins are encapsulated into inclusion bodies. Recombinant MpAPr1 was purified by using a nickel based column system and mass fingerprinting of the purified enzyme (MpAPr1) confirmed its identity. Purification was followed by refolding experiments, but yielded poor recovery of active enzymes. Unfortunately, recombinant expression of CaAPr1 could not be observed for reasons yet to be elucidated that may include the large sequence dissimilarities between CaAPr1 and MpAPr1. Finally, Southern blot analysis on the genomes of M. pulcherrima IWBT Y1123 and C. apicola IWBT Y1384 revealed that both possess at least one additional protease other than those previously described. Further analysis of the extracellular proteome of M. pulcherrima IWBT Y1123 also confirmed the presence of at least one enzyme able to hydrolyze BSA at a low pH. Unfortunately, mass fingerprinting performed on the entire extracellular proteome and on small groups of proteins thereof did not allow the identification of these enzymes. / AFRIKAANSE OPSOMMING: Gedurende fermentasie van druiwe sap skei gis ekstrasellulêre ensieme af wat ‘n aanmerklike impak op wyn eienskappe het. Terwyl die ekstrasellulêre proteïene vanaf Saccharomyces cerevisiae al gekarakteriseer is, bly die van nie-Saccharomyces spesies grootliks onbekend. Meeste van hierdie ensieme breek suiker polimere af of kataliseer die vrystelling van glikosiediese verbonde molekules. ‘n Ander klas van ensieme wat van belang is vir oenologie word voorgestel deur proteases wat in staat is daartoe om proteïenewaas te verminder, soos voorheen geraporteer is in literatuur, terwyl dit terselfde tyd die assimileerbare stikstof inhoud kan vermeerder. Die vrystelling van aminosure vanaf peptiede en/of proteïene wat as aroma voorlopers dien mag ook ‘n indirekte effek op die wyn se aroma profiel hê. In ‘n onlangse studie wat uitgevoer is by die Instituut vir Wynbiotegnologie (IWBT) was die volgordes van twee aspartiese proteases bepaal vanaf twee nie-Saccharomyces gis spesies wat geisoleer was uit Suid-Afrikaanse wyne. Die gene MpAPr1 en CaAPr1, was afsonderlik geisoleer vanuit twee nie- Saccharomyces giste, Metschnikowia pulcherrima IWBT Y1123 en Candida apicola IWBT Y1384. Egter was daar geen verder karakterisering van hierdie ensieme nie. Die doel van hierdie studie is om die bogenoemde gene in ‘n rekombinante bakteriese gasheer te kloneer vir uitdrukking en suiwering as ‘n eerste stap tot karakterisering van hul kinetiese eienskappe. Om in ag te neem dat sommige nie-Saccharomyces spesies meer as een protease produseer was ‘n aditionele mikpunt om vir nuwe suur proteases te soek binne M. pulcherrima IWBT Y1123. Klonering van hierdie gene en transformasie van die uitdrukkings vektore in E. coli was suksesvol. Optimale kondisies vir die induksie van ekspressie was bevestig na omvattende optimalisering. Verder, terwyl inheemse ekstraksie van die rekombinante proteïene onsuksesvol was, het denatureerende kondisies toegelaat vir suksesvolle ekstraksie, wat voorgestel het dat die rekombinante proteïene geinkapsileer word in inklusie liggame. Rekombinante MpAPr1 was gesuiwer deur gebruik te maak van ‘n niekel gebaseerde kolom sisteem en massa petied fingerafdrukke van die gesuiwerde ensiem (MpAPr1) het die identiteit bevestig. Suiwering was gevolg deur hervouing eksperimente, maar het swak opbrengste gelewer van die aktiewe ensiem. Ongelukkig kon die rekombinante ekspressie van CaAPr1 nie gevisualiseer word nie vir redes wat nog bevestig moet word, maar wat mag behels dat daar groot volgorde veskille tussen MpAPr1 en CaAPr1 kan wees. Uiteindelik was Southern blot hibridiseering analises uitgevoer op die genome van albei M. pulcherrima IWBT Y1123 en C. apicola IWBT Y1384 wat voorgestel het dat albei ten minste een addisionele protease, anders as die wat voorheen geidentifiseer was, bevat. Verder analiese van die ekstrasellulêre proteoom van M. pulcherrima IWBT Y1123 het ook die teenwoordigheid van ten minste een ensiem bevestig wat die vermoë het om BSA te hidroliseer by ‘n lae pH. Ongelukkig het massa peptied vingerafdrukbepaling wat uitgevoer was op die hele ekstrasellulêre proteoom en op klein groepe protein nie identifikasie van hierdie ensieme bevestig nie.

The cholinesterase (ChE) play an important role in the organophosphates and carbamates detection substances that are of high interest for environmental control, because these compounds are present in most pesticides applied to crops. The development of ChE biosensors to detect these contaminants with greater speed, sensitivity and selectivity, has the ability to quantify from a suitable transducer, the reduction of enzyme activity caused by contaminants. This study aimed to purify and characterize AChE of Prochilodus brevis brain for use in electrochemical tests. Gradients of pH, ionic strength and temperature, showed high activities in pH 8,5, 0,08M at ionic strength, 28Cº of temperature optimum and 37ºC of thermal stability for cell-free extract. Was applied salting out method in fractions 0-70% followed by 0-40% of (NH4)2SO4 as a refinement to liquid chromatography. The purification protocol 1 showed specific activity of 1.41 U/mg in 0-70% and 0-40% was 1.94 U/mg. The purification protocol 2, the 0-70% fraction had specific activity of 0.31 U/mg and 0-40% with 1.77 U/mg. After Sephacryl S-200 chromatography, showed specific activity for protocols 1 and 2 of 0,128U/mg and 0.2869 U/mg, respectively. The next stage of the Protocol 2 with DEAE-Sepharose was eluted peak with specific activity of 0.01326 U/mg. In the purification protocol 3, 0-70% have specific activity 0.310 U / mg, followed by 1,774 U/mg in 0-40%. After Sephacryl S-100, was obtain two peaks with a specific activity of 0.194 U/mg (ChE1) and 0.0873 U/mg (ChE2). SDS-PAGE of ChE 1 showed somewhat visible band of approximately 67kDa. Inhibition assays with ChE 1 had higher specificity for BW 284c51. Electrochemical tests with cell-free extract, dialyzed, ChE1 and ChE2, showed thiocholine (TCh) oxidation with better limits of detection and quantification limits for ChE1 and ChE2. The molecular modeling experiments showed favorable results in complex formation ChE-NTCPM. The study showed the isolation of ChE with catalytic activity for both enzymes, AChE and BuChE, with favorable adsorption properties in NTCPM in the development of enzymatic biosensor for environmental monitoring. / Conselho Nacional de Desenvolvimento Científico e Tecnológico / As colinesterases (ChE) desempenham um papel importante na detecção de organofosforados e carbamatos que são substâncias de alto interesse para o controle ambiental, pois estes compostos estão presentes na maioria dos pesticidas aplicados em lavouras. O desenvolvimento de biossensores a base de ChE para a detecção destes contaminantes com maior rapidez, sensibilidade e seletividade, tem a capacidade de quantificar, a partir de um transdutor adequado, a diminuição da atividade enzimática causada pelos contaminantes. Este trabalho teve como objetivo de purificar e caracterizar AChE de cérebro de Prochilodus brevis para o emprego em testes eletroquímicos. Os gradientes de pH, força iônica e temperatura, mostraram maiores atividades em pH 8,5, força iônica de 0,08M, temperatura ótima 28°C e estabilidade térmica de 37°C para extrato livre de células. Foi aplicado o método de precipitação salina em frações de 0-70% seguido de 0-40% de (NH4)2SO4 como refinamento para cromatografia líquida. O protocolo de purificação 1 apresentou atividade específica de 1,41 U/mg em 0-70%, enquanto 0-40% apresentou 1,94 U/mg. O protocolo de purificação 2, a fração 0-70% teve atividade específica de 0,31 U/mg e 0-40% de 1,77 U/mg. Após a cromatografia de sephacryl S-200 apresentou atividade específica para os protocolos 1 e 2 de 0,128U/mg e 0,2869 U/mg, respectivamente. Na continuidade do protocolo 2 com DEAE-sepharose o pico eluído apresentou atividade específica de 0,01326 U/mg. No protocolo de purificação 3, 0-70% tem atividade específica 0,310 U/mg, seguido de 1,774 U/mg em 0-40%. Após Sephacryl S-100 foi obtido dois picos com atividade específica de 0,194 U/mg (ChE1) e 0,0873 U/mg (ChE2). Eletroforese SDS-PAGE de ChE1 apresentou banda pouco visível de aproximadamente 67KDa. Os ensaios de inibição com ChE1 apresentaram maior especificidade para BW 284c51. Os testes eletroquímicos com extrato livre de célula, dialisado, ChE1 e ChE2, mostraram oxidação de tiocolina (TCh) com melhores limites de detecção e quantificação para ChE1 e ChE2. Os experimentos de modelagem molecular apresentaram resultados favoráveis na formação do complexo ChE-NTCPM. O estudo mostrou o isolamento de ChE com atividade catalítica para as duas enzimas, AChE e BuChE, com propriedades de adsorção favoráveis em NTCPM no desenvolvimento de biossensor enzimático para monitoramento ambiental.

abstract: Viral protein U (Vpu) is a type-III integral membrane protein encoded by the Human Immunodeficiency Virus-1 (HIV- 1). It is expressed in infected host cells and plays vital roles in down-regulation of CD4 receptors in T cells and also in the budding of virions. But, there remain key structure/function questions regarding the mechanisms by which the Vpu protein contributes to HIV-1 pathogenesis and thus, it makes for an attractive target to study the structural attributes of this protein by elucidating a structural model with X-ray crystallography. This study describes a multi-pronged approach of heterologous over-expression of Vpu. The strategies of purification and biophysical/ biochemical characterization of the different versions of the protein to evaluate their potential for crystallization are also detailed. Furthermore, various strategies employed for the crystallization of Vpu by both in surfo and in cubo techniques, and the challenges faced towards the structural studies of this membrane protein by characterization with solution Nuclear magnetic resonance (NMR) spectroscopy are also described. / Dissertation/Thesis / Doctoral Dissertation Molecular and Cellular Biology 2016

Orientador: Elias Basile Tambourgi / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-15T00:12:34Z (GMT). No. of bitstreams: 1 Elias_MoacyrJorge_D.pdf: 3281919 bytes, checksum: a06d734eab8439e1da9e683c7b3eb667 (MD5) Previous issue date: 2010 / Resumo: A bromelina, enzima presente no abacaxi, hidrolisa ligações peptídicas das proteínas; tem aplicação em diversas áreas envolvendo alimentos, medicina e nutrição animal. No abacaxi a bromelina está presente no talo, na polpa e na casca do fruto. Visando avaliar a bromelina presente no fruto brasileiro Ananás comosus L. Merril, variedade pérola, enfocando seu aproveitamento quando recuperada a partir dos resíduos da industrialização, foram pesquisadas, em comparação com a bromelina pura, condições de pH e temperatura para maior atividade, estabilidade térmica ao longo do tempo em várias temperaturas e a cinética da sua atividade catalítica, empregando caseína como substrato. O extrato foi obtido pela trituração da casca e do talo interno do fruto e a reação de hidrólise, com pH controlado, efetuada em reator com 75 mL de volume útil sob constante agitação. Após a reação foi retirada amostra, adicionada em tubo contendo ácido tricloroacético e centrifugado, analisando a absorbância do sobrenadante. Atividade e a cinética foram expressas em mmol tirosina / L.minuto pela absorbância a 280 nm dos aminoácidos aromáticos gerados na hidrólise da caseína. Foram empregadas três relações enzima / substrato (em massa): 1 / 25, 1 / 50 e 1 / 125 para os ensaios relativos ao planejamento experimental em estrela tendo como ponto central pH em 7,0 e temperatura de 35 °C, os resultados foram tratados fornecendo as equações do modelo e as superfícies de resposta; as equações foram tratadas matematicamente fornecendo gráficos da melhor atividade em função da temperatura; os resultados do planejamento experimental mostraram similaridade entre a bromelina dos resíduos do fruto e a bromelina pura tomada como padrão. Para a estabilidade térmica os ensaios foram efetuados determinando a atividade para a relação 1 / 25 sob temperaturas variando entre 25 °C e 62 °C ao longo de 180 minutos com duas faixas de pH: a de melhor atividade definida no planejamento experimental (5,5 a 6,5) e entre 3,3 e 3,5; os resultados foram tratados analisando o gráfico da atividade em função do tempo mostrando que o modelo de ordem um é adequado para descrever a inativação térmica da enzima e que ela ocorre de maneira mais acentuada na faixa de pH 3,3 a 3,5 com valor do fator de freqüência k0 (minuto-1) 2,5 x1032 vezes maior para o extrato. Os ensaios para determinar a cinética da atividade catalítica da bromelina sobre a caseína foram efetuados a temperatura constante de 35 °C e pH de máxima atividade definido no planejamento experimental para cada uma das três relações enzima / substrato estudadas; foram elaboradas as curvas da concentração de aminoácidos formados ao longo do tempo (zero a 15 minutos) e os resultados tratados calculando a derivada das curvas no tempo zero (velocidade inicial); o modelo de Michaelis - Menten mostrou ser adequado para descrever o mecanismo de hidrólise da caseína pela bromelina e os resultados indicam que os valores da velocidade máxima (Vmax) e da constante de Michaelis (Km) são maiores para o extrato dos resíduos do fruto do que para a bromelina pura. / Abstract: The bromelain, enzyme found in pineapple, hydrolyses peptide protein bonds; there is application in several areas involving food, medicine and animal nutrition. In pineapple the bromelain is present in the flesh, skin and core of the fruit. Aiming to evaluate the bromelain present in Brazilian fruit Ananas comosus L. Merril, pérola type, focusing its use from industrialization residues recovering, it was searched, comparing with pure bromelain, pH conditions and temperature for higher activity, thermal stability along the time under several temperatures and the kinetics of its catalytic activity, using casein as a substrate. The extract was obtained crushing the skin and core of the fruit and the hydrolysis reaction, with controlled pH, done in a 75 mL net volume reactor under constant stirring. After reaction a sample was taken, added to a tube with tri chloroacetic acid and centrifuged, analyzing the supernatant absorbance. Activity and kinetics were expressed as mmol of tyrosine / L.min from absorbance at 280 nm of aromatic amino acids generated by casein hydrolysis. Three enzyme / substrate ratio were employed (weight basis):1 / 25, 1 / 50 and 1 / 125 for star type experimental design assays with central point at 7.0 for pH and at 35 °C for temperature, the results were processed giving the model equation and surface responses, the equations were mathematically treated giving graphics of best activity as a function of temperature; the experimental design results showed similarity between bromelain from fruit residues and pure bromelain taken as reference. The assays for thermal stability were carried out by activity determination for 1 / 25 ratio under temperatures varying from 25 °C and 62 °C during 180 minutes for two pH ranges: that for best activity defined from experimental design (5.5 to 6.5) and between 3.3 to 3.5; the results were treated by the analysis of the graphics of activity as a function of time showing that the order one model is adequate to describe the enzyme thermal inactivation and that it is stronger at pH range of 3.3 to 3.5 with values of frequency factor k0 (minute-1) 2.5 x1032 times bigger for the extract.The assays to determine the kinetics of bromelain catalytic activity on casein were carried out at constant temperature of 35 °C and pH of maximum activity defined by experimental design for each one of the three studied enzyme / substrate ratio; curves were built for the concentration of formed amino acids along the time (from zero to 15 minutes) and the results treated calculating the curves derivative at time zero (initial rate); the Michaelis - Menten model showed to be adequate to describe the casein hydrolysis mechanism of casein by bromelain and the results indicate that the maximum reaction rate (Vmax) values and the Michaelis constant (Km) values are bigger for the fruit residues extract than that for pure bromelain. / Doutorado / Sistemas de Processos Quimicos e Informatica / Doutor em Engenharia Química

Orientador: Elias Basile Tambourgi / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-15T00:05:27Z (GMT). No. of bitstreams: 1 Barros_KleberVanioGomes_M.pdf: 726082 bytes, checksum: f7ee21d9c4e2a18b7c38d3e3a1baccd2 (MD5) Previous issue date: 2009 / Resumo: O curauá (Ananas erectifolius) é uma planta fibrosa proveniente da Amazônia brasileira, pertencente à família Bromeliaceae e ao gênero Ananas. A bromelina é uma protease de origem vegetal, obtida de diversas espécies da família Bromeliaceae. A bromelina tem utilização bastante difundida em processos industriais nas áreas alimentícia e farmacêutica. Efeitos antiinflamatórios da enzima, como também, o seu uso no tratamento da angina, na indigestão entre outros, estão documentados na literatura científica. Estudos de métodos para purificação de biomoléculas que viabilizem a sua obtenção em larga escala com custo reduzido são importantes áreas de pesquisa na biotecnologia. A extração líquido-líquido através de sistemas bifásicos aquosos (SBA) pode ser usada como técnica de pré-purificação de bioprodutos. Estes sistemas formam duas fases aquosas imiscíveis ou parcialmente miscíveis entre si. Podem ser formados a partir da mistura de dois polímeros ou de um polímero e um sal, a exemplo do sistema PEG (polietilenoglicol)/fosfato de potássio. Foi estudada a enzima bromelina derivada das folhas de ambas as variedades: curauá branco e curauá roxo. Pesquisou-se também a recuperação da enzima por extração líquido-líquido em sistemas de duas fases aquosas PEG/fosfato. Realizou-se ensaios em batelada para a extração e recuperação da enzima, utilizando como indicador o coeficiente de partição. Obteve-se fatores de purificação da enzima bromelina para o sistema fosfato de potássio e polietileno glicol 4000 e 6000, nos pH de 7,0; 8,0 e 9,0 a 25 °C. Estudou-se a partição em três diferentes "tie-lines". Analisou-se a influência do pH e do comprimento das linhas de amarração no coeficiente de partição da enzima. Na purificação da bromelina derivada das folhas do curauá branco, observou-se os melhores resultados no sistema bifásico aquoso PEG 4000/Fosfato em pH 7,0. Observou-se que o sistema PEG 6000/Fosfato em pH 7,0 apresentou os melhores resultados em relação à purificação da enzima bromelina derivada das folhas do curauá roxo. / Abstract: The curauá (Ananas erectifolius) is a fibrous plant from brazilian Amazon, belonging to the Bromeliaceae family and Ananas genus. Bromelain is a protease from vegetable origin, obtained from several species of this family. The bromelain has widespread use in industries process, such as in food and pharmaceutical areas. Antiinflammatory effects enzyme and also it uses in angina treatment, indigestion among others are documented in scientific literature. Methods' studies to purification of biomolecules that allow their achievement in large scale with low cost are important research's areas in biotechnology. The liquid-liquid extraction through aqueous twophase system (ATPS) can be used as technical of pre-purification of bioproduct. These systems form aqueous two-phase immiscible or partially miscible within themselves. They can be obtained by the addition of two polymers or one polymer and a salt, such as the PEG - poly(ethyleneglycol) - and potassium phosphate salt system. In the present report we characterized the bromelain enzyme that comes from the leaves of white curauá and purple curauá, and also investigated the recuperation of the enzyme by liquid-liquid extraction in aqueous two-phases PEG-phosphate systems (ATPS). The assays to extraction and recovery of the enzyme were carried out in batch mode, using the partition coefficient as indicator. Getting to factors purification of the enzyme bromelin to PEG 4000 and 6000 and potassium phosphate salt in ATPS, at pH 7.0, 8.0 and 9.0 at 25 ºC. We studied the partition through three different tie-lines. The influences of pH and tie-line length in partition coefficient of enzyme were analyzed. In the purification of bromelain derived from the leaves of white curauá, we observed the best results in PEG 4000/phosphate ATPS at pH 7.0. Furthermore, the system PEG 6000/phosphate at pH 7.0 showed the best results in relation to the purification of the enzyme bromelain derived from the leaves of purple curauá. / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química