The effects of temperature, reaction time, and substrate concentration on the incorporation of decanoic acid (DA) and alpha-linolenic acid (ALA), into cocoa butter, were compared, using an immobilized enzyme derived from Rhizomucor miehei. All variables had an effect on incorporation of DA and ALA into cocoa butter but effects were not equivalent for the two fatty acids. Thus, DA was not an adequate model fatty acid for the incorporation of ALA into cocoa butter. The highest ALA incorporation achieved was 77.3±1.3. Samples with ALA incorporated were prepared as “pure” and “blends”, and these exceeded the milk and dark chocolate Canadian Food and Drug Regulation guidelines for products making omega-3 fatty acid content claims. The highest %TAG content, 97.3±1.0%, was achieved for the 11.9wt% “blend” sample. Differential scanning calorimetry suggested that both “pure” and “blend” samples contained mainly form IV and V, with much smaller quantities of form II polymorphs.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Lipases, triacilglicerol Ãster hidrolases E.C. 3.1.1.3, sÃo enziÂmas que atuam nas ligaÃÃes Ãsteres de triacilglicerÃis, liberando Ãcidos orgÃnicos e glicerol. Podendo, em condiÃÃes microaquosas, catalisar a reaÃÃo reversa. Uma limitaÃÃo da utilizaÃÃo destas enzimas em processos industriais reside na falta de estabilidade operacional e na impossibilidade de sua reutilizaÃÃo na forma livre. O uso do sistema de organo-gÃis consiste em uma alternativa para a imobilizaÃÃo de enzimas, e para sua utilizaÃÃo na catÃlise enzimÃtica em meio orgÃnico. Neste sistema a enzima està localizada no centro micelar (centro aquoso) do organo-gel, eliminando o problemas como de estabilizar a enzima contra inativaÃÃo por um solvente nÃo-aquoso. O objetivo deste trabalho foi desenvolver derivados de lipases de Rhizomucor miehei imobilizadas em organo-gÃis à base de polÃmeros, visando à sÃntese de Ãsteres etÃlicos a partir de reaÃÃes de esterificaÃÃo de matÃrias-primas com elevado teor de Ãcidos graxos livres. Os suportes foram obtidos atravÃs de diferentes combinaÃÃes entre os componentes. Utilizaram-se polÃmeros gelatina (Gel), alginato (Alg) ou quitosana (Qui), fases orgÃnicas hexano (Hex) ou heptano (Hep) e os tensoativos dodecilsulfato de sÃdio (SDS) ou brometo de acetilmetilamÃnio (CTABr). Verificou-se a estabilidade tÃrmica da enzima na sua forma livre, determinando seu tempo de meia-vida. Na primeira etapa, foram produzidos derivados com e sem ativaÃÃo via glutaraldeÃdo 2% (v/v). A atividade enzimÃtica foi avaliada atravÃs hidrÃlise do p-nitrofenilbutirato (pNPB). Os derivados foram caracterizados quanto: fator de estabilidade a 60ÂC em relaÃÃo à enzima livre, eficiÃncia e rendimento de imobilizaÃÃo para assim determinar os melhores biocatalisadores. Dentre os catalisadores obtidos, os melhores apresentaram eficiÃncia de 4,1% e fator de estabilidade 30 vezes (Gel/SDS/Hex), eficiÃncia de 6,0% e fator de estabilidade 1,3 vezes (Alg/SDS/Hep) e eficiÃncia de 1,0% e fator de estabilidade de 2,3 vezes (Qui/SDS/Hep). Os suportes produzidos ativados com glutaraldeÃdo 2% (v/v) apresentaram baixas atividades e eficiÃncias, apesar de obterem valores bons de tempo de meia-vida e fator de estabilidade. Os derivados produzidos com o tensoativo CTABr apresentaram baixas atividades, eficiÃncias, tempo de meia-vida e fator de estabilidade. Na segunda fase, os derivados selecionados foram estudados quanto à carga mÃxima (50 U.g-1 a 500 U.g-1) de imobilizaÃÃo e eficiÃncia, nas temperaturas de 15ÂC e 25ÂC. Avaliou-se a aplicaÃÃo dos biocatalisadores na reaÃÃo de esterificaÃÃo do oleato de etila a partir de Ãcido oleico e etanol, variando a razÃo molar Ãcido/Ãlcool e utilizaÃÃo de agente dessecante (zeÃlitas). Verificou-se a estabilidade de estocagem sob 10ÂC por um perÃodo de 100 dias. Todos os derivados apresentaram melhores eficiÃncias utilizando carga de 50 U.g-1, apresentando valores de 4,2% e 4,8% (Gel/SDS/Hex), 2,0% e 2,3% (Alg/SDS/Hep) e 0,9% e 1,1% (Qui/SDS/Hep ) nas temperaturas de 15ÂC e 25ÂC, respectivamente. Nas reaÃÃes de esterificaÃÃo os derivados Gel/SDS/Hex e Alg/SDS/Hep obtiveram maiores conversÃes na razÃo molar Ãcido/Ãlcool 1:10, 72,9% e 16,9%, respectivamente. O derivado Qui/SDS/Hep obteve 80,0% de conversÃo na razÃo de 1:1. Com utilizaÃÃo de zeÃlitas o derivado Gel/SDS/Hex aumentou a conversÃo para 79,0% nas razÃes 1:1 e 1:5, os derivados Alg/SDS/Hep e Qui/SDS/Hep apresentaram decrÃscimo nas conversÃes. Durante os 100 dias de estocagem sob 10ÂC, os derivados Gel/SDS/Hex e Qui/SDS/Hep mantiveram atividade hidrolÃtica atà 40 dias, tendo um decrÃscimo ao longo do tempo. O derivado Alg/SDS/Hep obteve um tempo maior de 60 dias, apresentando tambÃm um decrÃscimo. / Lipases, triacylglycerol ester hydrolases EC 3.1.1.3, are enzymes that act on ester bonds of triacylglycerols, releasing organic acids and glycerol. May in microaquosas conditions, catalyze the reverse reaction. A limitation of using these enzymes in industrial processes is the lack of operational stability and the inability to re-use the free form. The use of organo-gels system is an alternative for the immobilization of enzymes and to their use in enzyme catalysis in organic media. In this system the enzyme is located in the micelle center (aqueous center) of the organo-gel, eliminating problems such as stabilizing the enzyme against inactivation by a non-aqueous solvent. The aim of this work was immobilize lipases from Rhizomucor miehei into organo - gels based on polymers for future application in ethyl esters synthesis through esterification of raw materials with high free fatty acids content. Supports were obtained using different combinations of components. It was used gelatin polymers (Gel), alginate (Alg) and / or chitosan (Chi), organic phases such as hexane (Hex) and heptane (Hep) and surfactants sodium dodecyl sulfate (SDS) or acetylmetylamonium bromide (CTABr). In the first step, derivatives were produced with and without glutaraldehyde 2% (v/v) activation. Enzymatic activity was measured by hydrolysis of p â nitrophenyl butyrate (PNPb). Biocatalysts were characterized as: stability at 60  C and compared to free enzyme, immobilization efficiency and yield factor, thus determining the best biocatalysts. Among the catalysts obtained, (Gel/SDS/Hex) showed the best efficiency of 4.1% , 30 âfold more stable; (Alg/SDS/Hep) with 6.0% efficiency , 1.3 âfold more stable and (Qui/SDS/Hep) with efficiency of 1.0 % , 1.3 âfold more stable than free lipase. Obtained supports activated with glutaraldehyde 2 % (v/v) showed lower activities and efficiencies, in despite of having good values for stability factor. Produced derivatives using surfactant CTABr presented low activity, efficiency and stability factor. In the second step, derivatives were analyzed as maximum load (50 U.g-1 a 500 U.g-1) enzyme immobilization and efficiency at 15  C and 25  C. It was evaluated biocatalysts application in ethyl oleate achievement in an esterification reaction, using oleic acid and ethanol, by varying molar ratio acid / alcohol with and without using of desiccant agent (zeolite) at 37  C and 24 h of reaction. Derivatives were submitted storage stability under 10  C studies, for a period of 100 days. All derivatives showed higher efficiencies using an initial enzyme loading of 50 U.g -1, with values of 4.2% and 4.8% (Gel/SDS/Hex), 2.0 % and 2.3 % (Alg/SDS/ Hep) and 0.9 % to 1.1% (Qui/SDS/Hep) at 15  C and 25  C, respectively. In esterification reactions, Gel/SDS/Hex and Alg/SDS/Hep derivatives showed higher conversions 72.9 % and 16.9 %, respectively, with molar acid / alcohol 1:10. The chemical derivative Qui/SDS/Hep presented 80.0 % conversion with molar acid / alcohol 1:1 ratio. Using zeolites, Gel/SDS/Hex conversion increased to 79.0 % using ratios of 1:1 and 1:5, the Alg/SDS/Hep and Qui/SDS/Hep presented a decreasing in conversions. During 100 days of storage at 10  C, Gel/SDS/Hex and Qui/SDS/Hep hydrolytic activity maintained up to 40 days and a decreasing during this period, however, Alg/SDS/ Hep achieved more than 60 days with activity.

<p> </p><p>A chemoselective catalyst is preferred in a chemical reaction where protecting groups otherwise are needed. The two lipases <em>Candida antarctica </em>lipase B and <em>Rhizomucor miehei</em> lipase showed large chemoselectivity ratios, defined as (<em>k_cat</em>/<em>K</em>_M)_OH/ (<em>k_cat</em>/<em>K</em>_M)_SH, in a transacylation reaction with ethyl octanoate as acyl donor and hexanol or hexanethiol as acyl acceptor (<strong>paper I</strong>). The chemoselectivity ratio of the uncatalyzed reaction was 120 in favour of the alcohol. Compared to the uncatalyzed reaction, the chemoselectivity was 730 times higher for <em>Candida antarctica </em>lipase B and ten times higher for <em>Rhizomucor miehei</em> lipase. The <em>K</em>_M towards the thiol was more than two orders of magnitude higher than the <em>K</em>_M towards the corresponding alcohol. This was the dominating contribution to the high chemoselectivity displayed by the two lipases. In a novel approach, <em>Candida antarctica </em>lipase B was used as catalyst for enzymatic synthesis of thiol-functionalized polyesters in a one-pot reaction without using protecting groups (<strong>paper II</strong>). Poly(e-caprolactone) with a free thiol at one of the ends was synthesized in an enzymatic ring-opening polymerization initiated with mercaptoethanol or terminated with either 3-mercaptopropionic acid or g-thiobutyrolactone.</p><p> </p>

Submitted by RONIVALDO RODRIGUES DA SILVA (rds.roni@yahoo.com.br) on 2016-03-01T13:46:53Z No. of bitstreams: 1 Tese Doutorado RONIVALDO R. SILVA.pdf: 3318357 bytes, checksum: 82fadd527a2ede34e2a0a237a881e8f8 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-03-01T18:27:48Z (GMT) No. of bitstreams: 1 silva_rr_dr_sjrp.pdf: 3318357 bytes, checksum: 82fadd527a2ede34e2a0a237a881e8f8 (MD5) / Made available in DSpace on 2016-03-01T18:27:48Z (GMT). No. of bitstreams: 1 silva_rr_dr_sjrp.pdf: 3318357 bytes, checksum: 82fadd527a2ede34e2a0a237a881e8f8 (MD5) Previous issue date: 2016-02-12 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Aspártico (E.C. 3.4.23), cisteíno (E.C. 3.4.22) e serino peptidases (E.C. 3.4.21) são endopeptidases, cujos modos de ação são dependentes de resíduos de ácido aspártico, cisteína e serina presentes no sítio catalítico, respectivamente. Atualmente, vários estudos são realizados na busca por novas enzimas com relevantes propriedades bioquímicas para aplicação industrial. Neste contexto, nós propomos a produção de enzimas em bioprocesso submerso, purificação, estudo das propriedades bioquímicas e determinação da especificidade catalítica das peptidases secretadas pelos fungos filamentosos Rhizomucor miehei, Phanerochaete chrysosporium e Leptosphaeria sp. Inicialmente, após produção por bioprocesso submerso, estas enzimas foram purificadas utilizando cromatografias de exclusão molecular e troca iônica. Em ensaios de inibidores na atividade enzimática, notamos inibição das peptidases por pepstatina A (R. miehei), ácido iodoacético/N-Etilmaleimida (P. chrysosporium) e fluoreto de fenil metil sulfonila (Leptosphaeria sp), sendo então definidas como aspártico, cisteíno e serino peptidases, respectivamente. Por SDS-PAGE (12%), as massas moleculares foram estimadas em 37 kDa (aspártico), 23 kDa (cisteíno) e 35 kDa (serino). O máximo de atividade proteolítica foi alcançado em pH 5,5 e 55 ºC para peptidase aspártica secretada por R. miehei; pH 7 e faixa de temperatura 45-55 ºC para cisteíno peptidase secretada por P. chrysosporium, e pH 7 e 45 ºC para serino peptidase secretada por Leptosphaeria sp. Sob efeito de incubação a diferentes pH, a peptidase aspártica mostrou-se estável em condições ácidas (pH 3-5); cisteíno peptidase foi estável em ampla faixa de pH (pH 4-9), e serino peptidase mostrou-se mais estável em condições com tendências alcalinas e pH ligeiramente ácido (pH 5-9). Em todas estas faixas de pH citadas, as peptidases apresentaram atividade proteolítica acima de 80% por 1 hora de incubação. Quanto à estabilidade térmica, a cisteíno peptidase mostrou-se mais termoestável dentre as três enzimas e serino peptidase descreveu a menor tolerância à temperatura. Em incubação com agentes desnaturantes, observamos redução na atividade proteolítica sob efeito de surfactantes iônicos (0,02-1%): dodecil sulfato de sódio (SDS) e brometo de cetil-trimetil amônio (CTAB); íon cobre II (5 mM); Ditiotreitol (DTT) e guanidina (ambos na faixa de 10-200 mM) para todas as peptidases. Por último, em estudo de especificidade catalítica destas enzimas, observamos a preferência por aminoácidos aromáticos (F e W), básicos (K e R) e apolares (em particular, resíduo de metionina) para peptidase aspártica. Alta especificidade descrita por cisteíno peptidase, cuja preferência catalítica é notória por aminoácidos básicos (K, H e R), especialmente na posição P3 e lisina-dependência para catálise na posição P'3. Em serino peptidase, notamos maior aceitação por aminoácidos apolares (G, I, L, M e V), básicos (H e R) e polares neutros (N e Q) para as diferentes posições avaliadas no substrato. / Aspartic (EC 3.4.23), cysteine (EC 3.4.22) and serine peptidases (EC 3.4.21) are endopeptidases whose modes of action are dependent on aspartic acid, cysteine and serine residues present in the catalytic site, respectively. Currently, several studies are conducted in the search for new enzymes with relevant biochemical properties for industrial application. In this context, we propose the production of enzymes in submerged bioprocess, purification, the study of biochemical properties and determining the catalytic specificity peptidases secreted by the filamentous fungus Rhizomucor miehei, Phanerochaete chrysosporium and Leptosphaeria sp. Initially, after production submerged bioprocess, these enzymes have been purified using size-exclusion and ion exchange chromatographies. In the effect of inhibitors on enzyme activity, we note peptidase inhibition by pepstatin A (R. miehei), iodoacetic acid/ N-Ethylmaleimide (P. chrysosporium) and phenyl methyl sulfonyl fluoride (Leptosphaeria sp), suggesting that these enzymes are aspartic, cysteine and serine peptidases, respectively. For SDS-PAGE (12%), molecular weights were estimated at 37 kDa (aspartic), 23 kDa (cysteine) and 35 kDa (serine). Maximum proteolytic activity was achieved at pH 5.5 and 55 °C for aspartic peptidase secreted by R. miehei; pH 7 and temperature range 45-55 °C for cysteine peptidase secreted by P. chrysosporium and pH 7 and 45 °C for serine peptidase secreted by Leptosphaeria sp. Under incubation at different pH effect, aspartic peptidase was stable under acidic conditions (pH 3-5); cysteine peptidase was stable in wide pH range (pH 4-9), and serine peptidase was more stable under alkaline conditions and pH slightly acidic (pH 5-9). In all these pH ranges mentioned, peptidases showed proteolytic activity above 80% by 1 hour incubation. As regards the thermal stability, cysteine peptidase was more thermostable enzyme and serine peptidase described the lowest temperature tolerance. In incubation with denaturing agents, we observed a decrease in proteolytic activity under the effect of ionic surfactant (0.02-1%) sodium dodecyl sulfate (SDS) bromide and cetyl-trimethyl ammonium bromide (CTAB); copper (II) ion (5 mM); Dithiothreitol (DTT) and guanidine (both in the range of 10-200 mM) for all peptidases. Finally, the study of catalytic specificity of these enzymes, we found a preference for aromatic amino acids (F and W), basic (K and R) and nonpolar (in particular, methionine residue) to aspartic peptidase. High specificity described by cysteine peptidase, which a catalytic preference is notorious for basic amino acids (K, R and H), especially in position P3 and lysine-dependence for catalysis at position P'3. In serine peptidase, for different evaluated positions, we noticed greater acceptance by nonpolar amino acids (G, I, L, M and V), basic (M and R) and neutral polar (N and Q).

A chemoselective catalyst is preferred in a chemical reaction where protecting groups otherwise are needed. The two lipases Candida antarctica lipase B and Rhizomucor miehei lipase showed large chemoselectivity ratios, defined as (kcat/KM)OH / (kcat/KM)SH, in a transacylation reaction with ethyl octanoate as acyl donor and hexanol or hexanethiol as acyl acceptor (paper I). The chemoselectivity ratio of the uncatalyzed reaction was 120 in favour of the alcohol. Compared to the uncatalyzed reaction, the chemoselectivity was 730 times higher for Candida antarctica lipase B and ten times higher for Rhizomucor miehei lipase. The KM towards the thiol was more than two orders of magnitude higher than the KM towards the corresponding alcohol. This was the dominating contribution to the high chemoselectivity displayed by the two lipases. In a novel approach, Candida antarctica lipase B was used as catalyst for enzymatic synthesis of thiol-functionalized polyesters in a one-pot reaction without using protecting groups (paper II). Poly(e-caprolactone) with a free thiol at one of the ends was synthesized in an enzymatic ring-opening polymerization initiated with mercaptoethanol or terminated with either 3-mercaptopropionic acid or g-thiobutyrolactone.