Purpose. The present work hypothesized that proteolytic dissolution of intervertebral discs could induce biomechanical change comparable to the change observed in natural disc degeneration. A method to do such could be utilized for in vitro research where intersample differences in geometry and chemical makeup render it difficult to compare and aggregate results into generalized conclusions. Methods. Forty-one bovine coccygeal intervertebral discs were isolated with individual functional spinal units. Samples were loaded in three modes: compression/tension, flexion/extension, and axial rotation. The anulus fibrosus of each disc was injected with 200µl trypsin or fetal bovine serum (control) and incubated for an allotted period: 30 minute, 60 minutes, or 180 minutes. Mechanical loading was repeated and the load-displacement responses before and after treatment were compared as were the differences between each time group. Results. Significant change was observed in the discs' total range (stiffness), low range (laxity), and hysteresis. Changes in load-displacement response were observed to be correlated with both treatment and time. Conclusions. Enzymatic degeneration of intervertebral discs shows promise as a means to further understanding of disc mechanics in varying levels of degeneration. In virtually all cases, the trypsinized discs exhibited the increased joint laxity and decreased stiffness that is associated with early stage, natural disc degeneration.

The antibody immunoglobulin G (IgG) can be tryptically digested into smaller peptides. This study attempted to develop a separation method for those peptides using RP-HPLC with a C18 column at room temperature. Optimizing separation of trypsin cleaved cytochrome C was used as a guideline before analyzing IgG. The optimized analysis of Cytochrome C was performed at wavelength 280nm (UV) and methanol was used as an organic solvent in mobile phase (B). A fast gradient to 100% mobile phase B with low flow rate gave favorable results for cytochrome C. A slow gradient to 100% mobile phase B was suited for IgG separation. The optimized gradient elution of cytochrome C and IgG was performed at 0.3 and 0.8 ml/min, respectively. / Antikroppen Immunoglobulin G (IgG) kan klyvas till peptider med enzymet trypsin. Under denna studie ska utvecklades en separationsmetod för dessa peptider med RP-HPLC. Separationen utfördes med en C18 kolonn i rumstemperatur. Först optimerades en separation av trypsin-klyvt cytokrom C vars optimerade parametrar sedan användes som grund för IgG-separation. Optimeringen utfördes vid våglängden 280 nm(UV) och metanol användes som organiskt lösningsmedel i mobil fas (B). En snabb gradient upp till 100% B med låg flödeshastighet gav mest gynnsamt resultat för cytokrom C. Separationen av IgG gynnades av ett högt flöde och en långsam gradient till 100% B. Den optimerade gradientelueringen för cytokrom C och IgG gjordes vid flödet 0.3 respektive 0.8 ml/min.

No description available.

Despite tremendous advances in mass spectrometry instrumentation and mass spectrometry-based methodologies, global protein profiling of organellar, cellular, tissue and body fluid proteomes in different organisms remains a challenging task due to the complexity of the samples and the wide dynamic range of protein concentrations. In addition, large amounts of produced data make result exploitation difficult. To overcome these issues, further advances in sample preparation, mass spectrometry instrumentation as well as data processing and data analysis are required. The presented study focuses as first on the improvement of the proteolytic digestion of proteins in in-gel based proteomic approach (Gel-LCMS). To this end commonly used bovine trypsin (BT) was modified with oligosaccharides in order to overcome its main disadvantages, such as weak thermostability and fast autolysis at basic pH. Glycosylated trypsin derivates maintained their cleavage specifity and showed better thermostability, autolysis resistance and less autolytic background than unmodified BT. In line with the “accelerated digestion protocol” (ADP) previously established in our laboratory modified enzymes were tested in in-gel digestion of proteins. Kinetics of in-gel digestion was studied by MALDI TOF mass spectrometry using 18O-labeled peptides as internal standards as well as by label-free quantification approach, which utilizes intensities of peptide ions detected by nanoLC-MS/MS. In the performed kinetic study the effect of temperature, enzyme concentration and digestion time on the yield of digestion products was characterized. The obtained results showed that in-gel digestion of proteins by glycosylated trypsin conjugates was less efficient compared to the conventional digestion (CD) and achieved maximal 50 to 70% of CD yield, suggesting that the attached sugar molecules limit free diffusion of the modified trypsins into the polyacrylamide gel pores. Nevertheless, these thermostable and autolysis resistant enzymes can be regarded as promising candidates for gel-free shotgun approach. To address the reliability issue of proteomic data I further focused on protein identifications with borderline statistical confidence produced by database searching. These hits are typically produced by matching a few marginal quality MS/MS spectra to database peptide sequences and represent a significant bottleneck in proteomics. A method was developed for rapid validation of borderline hits, which takes advantage of the independent interpretation of the acquired tandem mass spectra by de novo sequencing software PepNovo followed by mass-spectrometry driven BLAST (MS BLAST) sequence similarity searching that utilize all partially accurate, degenerate and redundant proposed peptide sequences. It was demonstrated that a combination of MASCOT software, de novo sequencing software PepNovo and MS BLAST, bundled by a simple scripted interface, enabled rapid and efficient validation of a large number of borderline hits, produced by matching of one or two MS/MS spectra with marginal statistical significance.

Background: Trypsinogen is the inactive precursor of trypsin, a serine protease that cleaves proteins and peptides after arginine and lysine residues. In this study, human trypsinogen was used as a model protein to study the influence of electrostatic forces on protein–protein interactions. Trypsinogen is active only after its eight-amino-acid-long activation peptide has been cleaved off by another protease, enteropeptidase. Trypsinogen can also be autoactivated without the involvement of enteropeptidase. This autoactivation process can occur if a trypsinogen molecule is activated by another trypsin molecule and therefore is based on a protein–protein interaction. Results: Based on a rational protein design based on autoactivation-defective guinea pig trypsinogen, several amino acid residues, all located far away from the active site, were changed to modify the surface charge of human trypsinogen. The influence of the surface charge on the activation pattern of trypsinogen was investigated. The autoactivation properties of mutant trypsinogen were characterized in comparison to the recombinant wild-type enzyme. Surface-charged trypsinogen showed practically no autoactivation compared to the wild-type but could still be activated by enteropeptidase to the fully active trypsin. The kinetic parameters of surface-charged trypsinogen were comparable to the recombinant wild-type enzyme. Conclusion: The variant with a modified surface charge compared to the wild-type enzyme showed a complete different activation pattern. Our study provides an example how directed modification of the protein surface charge can be utilized for the regulation of functional protein–protein interactions, as shown here for human trypsinogen.

Polyelektrolytmikrokapseln (PEMC) stellen ein neuartiges System künstlicher Zellen dar. Durch Einbringen von z.B. Hämoglobin in solche PEMC können sie als  künstliche Erythrozyten den Gastransport im Organismus unterstützen bzw. übernehmen. Es muss jedoch berücksichtigt werden, dass jede Zelle des Säugtierorganismus zur Aufrechterhaltung ihrer Funktion Enzyme benötigt, die ihre Stoffwechselfunktionen katalysieren. Um sich der Lösung dieses Problems bei der Entwicklung eines künstlichen Erythrozyten schrittweise zu nähern, wurde als Modellenzym Trypsin ausgewählt. Es wurden Polyelektrolytmikrokapseln (PEMC) auf der Basis von Erythrozyten durch Selbstassemblierung von Polynatriumstyrensuphonat (PSS) und Polyallylamino-hydrochlorid (PAH) hergestellt ((PSS/PAH)2PSS), und anschliessend nach der Layer-by-Layer Methode (LbL) alternierend mit Trypsin und den Polyelektrolyten (PE) PSS, Alginat oder Dextransulphat weiterbeschichtet. Der Schichtenaufbau wurde durch Zellelektrophorese, konfokale Laserscanning-mikroskopie (CLSM), Durchflusszytometrie (FACS) und photometrische Proteinbestimmung charakterisiert und quantifiziert. Die Aktivität des an der PEMC-Membran immobilisierten Enzyms wurde untersucht und mit der Aktivität freien Trypsins verglichen. Weiterhin wurden pH-Profile von freiem Enzym mit denen des immobilisierten Trypsins verglichen. Der Schichtaufbau aus Trypsin und den unterschiedlichen Polyelektrolyten wurde anhand der Änderung der elektrophoretischen Mobilität beim Aufbringen jeder Schicht, sowie durch die Zunahme der photometrisch bestimmten Proteinmenge pro PEMC charakterisiert. Außerdem wurde Trypsin mit Fluoreszeinisothiozyanat (FITC) markiert und in den Beschichtungsserien die Zunahme der flowzytometrisch bestimmten Fluoreszenz-Intensität mit jeder aufgebrachten FITC-Trypsin Schicht beobachtet. Die Aktivität des an den PEMC immobilisierten Trypsins beträgt etwa 30% der Aktivität freien Trypsins gleicher Konzentration. Es konnte gezeigt werden, dass sich Trypsin im Rahmen eines Schichtaufbaus nach der LbL-Technologie in die Membran der verwendeten PEMC einbringen lässt. Dabei behält das Enzym einen Teil seiner Funktion. / Artificial cells are not only used to study the biological processes of living cells, they also serve as micro reactors to provide certain functions in the organism. Polyelectrolyte microcapsules (PEMC) represent a new approach to artificial cell studies. When filled with hemoglobin, PEMC are able to perform the erythrocyte gas exchange. This work shows the general possibility of integrating enzymes into the PEMC membrane. PEMC were composed using the layer-by-layer (l-b-l) technique. Glutaraldehyde stabilized human red blood cells (RBC) served as templates and were coated with five layers poly(styrene sulfonate) (PSS) and poly(allylaminehydrochloride) (PAH). After decomposition of the RBC by sodium hypochlorite, the PEMC were coated with ten layer pairs of trypsin and either PSS or alginate. The trypsin layer growth was followed performing measurements by cell electrophoresis, confocal laser scanning microscopy (CLSM), flow cytometry (FACS) and protein determination according to Lowry after each adsorption step. Results showed a continuous layer buildup for both polyelectrolytes and no desorption of trypsin. The amount of immobilized enzyme was larger for the coating series with trypsin/PSS compared to that with trypsin/alginat. This was concluded as a result of PSS/trypsin complex formation. Normalizing the enzym activity to the amount of adsorbed trypsin no significant differences between the activity of PSS-PEMC and alginate-PEMC were found. Further experiments prove that PSS inhibits the enzyme activity and alginat does not.

Esse trabalho teve como objetivo a determinação da estrutura tridimensional do inibidor de tripsina purificado de sementes de Enterolobium contortisiliquum (EcTI) e a modelagem molecular dos complexos EcTItripsina, EcTI-quimotripsina , EcTI-trombina, EcTI-fator Xa, e suas análises. O EcTI possui 19kDa de peso molecular inibe tripsina, quimotripsina, calicreína plasmática humana, plasmina humana e fator Xlla, mas não inibe fator Xa e ativador de plasminogênio. Monocristais apropriados à coleta de dados de difração de raios-X foram obtidos na condição 50 do fatorial da Hampton (PEG8000 - 0,5M, LiSO4 - 0,5M) através da técnica de acupuntura em gel à temperatura constante de 15&#176C após três semanas. O grupo espacial encontrado foi o P21 com uma molécula na unidade assimétrica. Os dados de difração foram coletados num detetor de placas de imagem MAR345 na linha de Cristalografia de Proteínas (PCr) no Laboratório Nacional de Luz Síncrotron (LNLS) em Campinas até uma resolução de 1,96&#197, completeza de 87% e Rsym=10,3%. A estrutura foi resolvida por Substituição Molecular tendo-se como molde a estrutura do inibidor de tripsina proveniente de Erythrina caffra que apresenta 39% de identidade seqüencial com a seqüência primária do EcTI. Divergências entre a seqüência primária esperada e a observada no mapa de densidade eletrônica levaram à suposição da existência de isoformas para este inibidor. Acatando esta hipótese e supondo que a isoforma cristalizada era diferente da isoforma cuja seqüência foi publicada, mudanças na seqüência guiadas pelo mapa de densidades foram realizadas. Um total de 33 substituições e 1 inserção foram feitos. Diferentemente das tentativas de refinamento com a seqüência original, após as substituições o refinamento convergiu para valores aceitáveis de Rfactor=17% e Rfree=25%. A estrutura apresenta o enovelamento &#946-trefoil com uma pseudo simetria de ordem 3. Os grampos de cabelo presentes na estrutura são espiralados mas isto não é resultado de repetições sistemáticas nos ângulo &#934/&#936 como esperado. Baseado nesta estrutura cristalográfica, um modelo da seqüência original foi construído por modelagem por homologia. A avaliação do modelo em termos de estereoquímica e compatibilidade estrutura-seqüência mostra uma boa qualidade, mesmo existindo a formação de uma ponte salina enterrada no núcleo hidrofóbico da molécula. Estruturas cristalográficas de complexos entre tripsina, quimotripsina, fator Xa e trombina foram usados para gerar modelos de complexos entre as serinoproteases correspondentes e o EcTI. A falta de atividade de EcTI contra fator Xa e trombina pode ser atribuída à incompatibilidade química e estrutural na interface do complexo. / The principal objective of this work was the 3D structural determination of a Trypsin inhibitor from Enterolobium contortisiliquum (EcTI) seeds as well as the modeling of the complexes between EcTI and trypsin, chymotrypsin, thrombin and factor Xa and their subsequent analysis. The inhibitor has a molecular weight of 19.5 kDa and inhibits trypsin, chymotrypsin, human plasma kallikrein, human plasmin and factor Xlla but not factor Xa and tissue type plasminogen activator. A single crystal appropriate for X-ray data collection was grown using condition 50 of Hampton\'s Research fatorial (PEG8000 - 15%, LiSO4 - 0.5mM) by the gel acupuncture technique at 15&#176C. The crystal grew in three weeks in the space group P21 with one molecule in the assymetric unit. Crystallographic data were acquired using an image plate detector MAR345 on the Protein Crystallography beam line at the Laboratório Nacional de Luz Síncrotron (LNLS), Campinas, out to 1,96&#197 resolution, with a completeness of 87% and Rsym= 10.3%. The structure was solved by the Molecular Replacement method using the previous determined structure of the trypsin inhibitor from Erythrina caffra which presented 39% sequence identity to EcTI. Discrepancies in the primary structure, as observed in the electron density map led to the supposition of the existence of isoforms for this particular inhibitor. In total 33 substitutions and 1 insertion were made. In contrast with the attempts made with the original sequence, after the amino acids were substituted the refinement converged to acceptable values for Rfactor=17% and Rfree=25%. The 3D fold of EcTI is a &#946-trefoil as expected. The hairpins present in this fold are coiled coils, but not as a result of the systematic alternation of the &#934/&#936 angles as expected. Using the crystallographic structure as a template a homology model for the original sequence was built. The model evaluation in terms of stereochemistry and structure-sequence compatibility showed it to be of generally good quality, despite the presence of a salt bridge buried in the hydrophobic core. Docking experiments using crystallographic structures of trypsin, chymotripsin, factor Xa and thrombin complexed with their respective inhibitors were undertaken. The lack of EcTI activity against factor Xa and thrombin is predicted to be due to chemical and structural incompatibility at the complex interface.

Esse trabalho teve como objetivo a determinação da estrutura tridimensional do inibidor de tripsina purificado de sementes de Enterolobium contortisiliquum (EcTI) e a modelagem molecular dos complexos EcTItripsina, EcTI-quimotripsina , EcTI-trombina, EcTI-fator Xa, e suas análises. O EcTI possui 19kDa de peso molecular inibe tripsina, quimotripsina, calicreína plasmática humana, plasmina humana e fator Xlla, mas não inibe fator Xa e ativador de plasminogênio. Monocristais apropriados à coleta de dados de difração de raios-X foram obtidos na condição 50 do fatorial da Hampton (PEG8000 - 0,5M, LiSO4 - 0,5M) através da técnica de acupuntura em gel à temperatura constante de 15&#176C após três semanas. O grupo espacial encontrado foi o P21 com uma molécula na unidade assimétrica. Os dados de difração foram coletados num detetor de placas de imagem MAR345 na linha de Cristalografia de Proteínas (PCr) no Laboratório Nacional de Luz Síncrotron (LNLS) em Campinas até uma resolução de 1,96&#197, completeza de 87% e Rsym=10,3%. A estrutura foi resolvida por Substituição Molecular tendo-se como molde a estrutura do inibidor de tripsina proveniente de Erythrina caffra que apresenta 39% de identidade seqüencial com a seqüência primária do EcTI. Divergências entre a seqüência primária esperada e a observada no mapa de densidade eletrônica levaram à suposição da existência de isoformas para este inibidor. Acatando esta hipótese e supondo que a isoforma cristalizada era diferente da isoforma cuja seqüência foi publicada, mudanças na seqüência guiadas pelo mapa de densidades foram realizadas. Um total de 33 substituições e 1 inserção foram feitos. Diferentemente das tentativas de refinamento com a seqüência original, após as substituições o refinamento convergiu para valores aceitáveis de Rfactor=17% e Rfree=25%. A estrutura apresenta o enovelamento &#946-trefoil com uma pseudo simetria de ordem 3. Os grampos de cabelo presentes na estrutura são espiralados mas isto não é resultado de repetições sistemáticas nos ângulo &#934/&#936 como esperado. Baseado nesta estrutura cristalográfica, um modelo da seqüência original foi construído por modelagem por homologia. A avaliação do modelo em termos de estereoquímica e compatibilidade estrutura-seqüência mostra uma boa qualidade, mesmo existindo a formação de uma ponte salina enterrada no núcleo hidrofóbico da molécula. Estruturas cristalográficas de complexos entre tripsina, quimotripsina, fator Xa e trombina foram usados para gerar modelos de complexos entre as serinoproteases correspondentes e o EcTI. A falta de atividade de EcTI contra fator Xa e trombina pode ser atribuída à incompatibilidade química e estrutural na interface do complexo. / The principal objective of this work was the 3D structural determination of a Trypsin inhibitor from Enterolobium contortisiliquum (EcTI) seeds as well as the modeling of the complexes between EcTI and trypsin, chymotrypsin, thrombin and factor Xa and their subsequent analysis. The inhibitor has a molecular weight of 19.5 kDa and inhibits trypsin, chymotrypsin, human plasma kallikrein, human plasmin and factor Xlla but not factor Xa and tissue type plasminogen activator. A single crystal appropriate for X-ray data collection was grown using condition 50 of Hampton\'s Research fatorial (PEG8000 - 15%, LiSO4 - 0.5mM) by the gel acupuncture technique at 15&#176C. The crystal grew in three weeks in the space group P21 with one molecule in the assymetric unit. Crystallographic data were acquired using an image plate detector MAR345 on the Protein Crystallography beam line at the Laboratório Nacional de Luz Síncrotron (LNLS), Campinas, out to 1,96&#197 resolution, with a completeness of 87% and Rsym= 10.3%. The structure was solved by the Molecular Replacement method using the previous determined structure of the trypsin inhibitor from Erythrina caffra which presented 39% sequence identity to EcTI. Discrepancies in the primary structure, as observed in the electron density map led to the supposition of the existence of isoforms for this particular inhibitor. In total 33 substitutions and 1 insertion were made. In contrast with the attempts made with the original sequence, after the amino acids were substituted the refinement converged to acceptable values for Rfactor=17% and Rfree=25%. The 3D fold of EcTI is a &#946-trefoil as expected. The hairpins present in this fold are coiled coils, but not as a result of the systematic alternation of the &#934/&#936 angles as expected. Using the crystallographic structure as a template a homology model for the original sequence was built. The model evaluation in terms of stereochemistry and structure-sequence compatibility showed it to be of generally good quality, despite the presence of a salt bridge buried in the hydrophobic core. Docking experiments using crystallographic structures of trypsin, chymotripsin, factor Xa and thrombin complexed with their respective inhibitors were undertaken. The lack of EcTI activity against factor Xa and thrombin is predicted to be due to chemical and structural incompatibility at the complex interface.

The presence of pathogens in semen can compromise the outcome of assisted reproductive treatment, together with the possibility of the female partner or offspring becoming infected. This is cause for concern, especially in South Africa with a high prevalence of HIV-1. Most of these infected individuals are in their reproductive years with the desire to have their own genetically related children. Therefore, assisted reproductive treatment with effective risk reduction procedures, such as semen processing for the elimination of these pathogens is crucial. However, during sperm preparation by standard discontinuous density gradient centrifugation, the supernatant is aspirated to allow access to the purified sperm pellet. Pathogens from the upper layers can adhere to the inside surface of the test tube and flow down to re-infect the purified sperm sample. The use of a centrifuge tube insert may prevent the re-contamination of sperm samples after discontinuous density gradient centrifugation. Furthermore, seminal pathogens can bind specifically or non-specifically to spermatozoa, rendering semen decontamination procedures ineffective. Serine proteases, such as trypsin, have been demonstrated to effectively inactivate viruses and to break pathogen-sperm bonds. However, the addition of a protease to density gradient layers during semen processing could have a negative impact on sperm parameters. This research was therefore aimed towards the determination of: i) The effect of semen processing with trypsin and trypsin inhibitor on sperm parameters. ii) The prevalence of various bacteria in semen samples from men attending the Reproductive and Endocrine Unit at Steve Biko Academic Hospital. iii) The effectiveness of semen processing by discontinuous density gradient centrifugation with a centrifuge tube insert, for the elimination of some of the most prevalent bacteria, white blood cells and in vivo derived HIV-1. Evaluation of sperm parameters after semen processing indicated that trypsin and trypsin inhibitor did not have an impact on sperm mitochondrial membrane potential, vitality, motility and zona binding potential, or acrosin activity, respectively. Seminal bacteria were highly prevalent in patients wishing to participate in the Unit’s assisted reproductive program, with 49.5% of semen samples presenting with positive bacterial cultures. Semen processing by means of discontinuous density gradient centrifugation with the tube insert, eliminated significantly more in vitro derived (spiked) bacteria and white blood cells from semen compared to processing without the insert. Furthermore, the semen decontamination procedure was effective in removing HIV-1 RNA from 100% of samples and proviral DNA from 98.1% of semen samples from HIV-1 sero-positive patients. The effectiveness of discontinuous density gradient centrifugation for the elimination of seminal pathogens could, therefore, be improved by the addition of trypsin to the upper density layer, without supplementing the bottom layer with trypsin inhibitor. Additionally, semen decontamination efficiency could also be improved by the prevention of re-contamination of processed sperm samples by the utilization of a tube insert during discontinuous density gradient centrifugation. / Thesis (PhD)--University of Pretoria, 2014. / gm2014 / Obstetrics and Gynaecology / unrestricted

Background: Trypsinogen is the inactive precursor of trypsin, a serine protease that cleaves proteins and peptides after arginine and lysine residues. In this study, human trypsinogen was used as a model protein to study the influence of electrostatic forces on protein–protein interactions. Trypsinogen is active only after its eight-amino-acid-long activation peptide has been cleaved off by another protease, enteropeptidase. Trypsinogen can also be autoactivated without the involvement of enteropeptidase. This autoactivation process can occur if a trypsinogen molecule is activated by another trypsin molecule and therefore is based on a protein–protein interaction. Results: Based on a rational protein design based on autoactivation-defective guinea pig trypsinogen, several amino acid residues, all located far away from the active site, were changed to modify the surface charge of human trypsinogen. The influence of the surface charge on the activation pattern of trypsinogen was investigated. The autoactivation properties of mutant trypsinogen were characterized in comparison to the recombinant wild-type enzyme. Surface-charged trypsinogen showed practically no autoactivation compared to the wild-type but could still be activated by enteropeptidase to the fully active trypsin. The kinetic parameters of surface-charged trypsinogen were comparable to the recombinant wild-type enzyme. Conclusion: The variant with a modified surface charge compared to the wild-type enzyme showed a complete different activation pattern. Our study provides an example how directed modification of the protein surface charge can be utilized for the regulation of functional protein–protein interactions, as shown here for human trypsinogen.