Gelatin was extracted from shark and salmon skins by an enzyme aided process. A three factor, two level central composite rotatable design was used to optimize the process. The factors were namely, enzyme: dry fish skin weight ratio, incubation time, and temperature. The data were analyzed by response surface methodology to determine the optimum conditions for the deproteinization, demineralization and extraction process variables. / Optimum conditions for deproteinization of shark skin by trypsin was about 25°C for 3h, and an E/S ratio of 0.08% (w/w). That for salmon was optimum at 25°C for 1 h with an E/S ratio of 1:1000. The ash content of the shark skins was reduced to over 80% at optimum demineralization conditions of 0.7M citric acid at 25°C for 3h. / Demineralised salmon skins treated with pepsin at an E/S ratio of 0.02% (w/w) for 1h at 25°C resulted in maximum gelatin yield ranging from 7--8%. For shark, the maximum yield was between 18--20% at an E/S ratio of 0.02% (w/w) for 3h at 25°C. The chemical and enzyme treatments had an effect on the viscosity, bloom value and molecular weight for both salmon and shark gelatins.

The purification of pepsinogen from the stomach of red perch using aqueous two phase systems (ATPS) formed by polyethylene glycol (PEG) and salt at 4°C was optimized. Salt type, salt concentration, PEG molecular weight and PEG concentration had significant effects on total volume (TV), volume ratio (VR), enzyme activity (AE), protein content (CP), specific activity (SA), purification fold (PF) and recovery yield (RY). (NH4)2SO4 at 15% w/w concentration was selected as the optimum salt type and concentration. PEG 1500 at 18% w/w concentration was selected as the optimum PEG molecular weight and concentration. 15% (NH4)2SO4-18% PEG 1500, the optimal ATPS, was compared with ammonium sulfate fractionation (ASF). ATPS gave better partition of pepsinogen (SA of 5.40 U/mg, PF of 5.20 and RY of 86.6%) than ASF (SA of 2.55 U/mg, PF of 2.46, RY of 70.4%). / This is the electronic copy of partition of pepsinogen in aqueous two phase system method.

The mass of five proteins (Bovine serum albumin (BSA), casein, lysozyme, ovalbumin and pepsin) adsorbed to five different membrane materials (of various hydrophobicities) was quantified using a static system and analysed to establish any trends. Comparing the results from the five membranes it seems that there were no obvious trends between the protein masses adsorbed indicating that it may not be just one aspect of protein structure that is important in the adsorption process. Many investigations have indicated that the protein may undergo a conformational change during the adsorption process. Disulphide bridges contribute readily to the stability of the protein molecule and it was hypothesised that if such a structural change occurred, it would result in the breakage of these covalent bonds. To this end, the free thiol group content of the proteins was quantified before and after adsorption.

The pepsinogens and pepsins of cobra, mole snake and puff adder have been studied. The pepsinogens of all three species fall into two distinct groups, here designated PI and PII. At least the latter group, in all cases, shows substantial microheterogeneity. Physicochemical studies suggest that the cobra and puff adder PII groups are more similar to each other than either is to the mole snake PII group. Kinetic studies indicate that, in the cobra and mole snake, the PI and PII pepsins differ in their Arrhenius activation energies. Such difference is smaller, or absent, in the case of the puff adder PI and PII pepsins. These characteristics of the pepsins are assessed in the context of the differences between the oral secretions of the three species studied. The suggestion is advanced that the puff adder's strongly proteolytic venom has influenced certain properties of its gastric proteases.

No description available.

Introduction: The presence of an endotracheal tube (ETT) increases the risk for microaspiration of secretions around the ETT. Biomarkers of pepsin and salivary amylase may be used to identify microaspiration in intubated patients because of their naturally occurring presence in the stomach or oral cavity and non-occurrence in the respiratory tract. Microaspiration may be difficult to detect until pulmonary complications, such as lung injury or infection, occur. This study assessed the presence of pepsin and salivary amylase in oral and tracheal secretions of ventilated adults. Method(s): This is a secondary analysis of data collected from 11 critically ill, adult patients on mechanical ventilation (MV) enrolled in a study to identify cues for ETT suctioning. Two paired samples of oral and tracheal secretions were suctioned when clinically indicated. Tracheal secretions were suctioned with a closed system, and oral secretions were obtained with an oropharyngeal catheter. Specimens were analyzed for total pepsin, pepsin A, pepsin C, and salivary amylase according to established assays. Results: Of 11 subjects, the majority were men (n=8), on enteral feedings (n=9) via a feeding tube placed in the stomach (n=7), and intubated with a continuous subglottic suction ETT (n=8). Median values: age, 62 years; duration of MV, 5.5 days; ETT cuff pressure 24 cm H2O; head of bed, 30degrees]. Pepsin was in measured in both oral (30.5 ng/mL; n=8) and tracheal secretions (11.1 ng/mL; n=7); Similar findings were noted for pepsin A (oral 14.7 ng/mL, n=7; sputum 7.4 ng/mL, n=6) and pepsin C (oral 14.7, n=7; tracheal 7.4, n=6). Salivary amylase (mean micro]mol/min/mL) was present in all oral secretions (359.8) and in the sputum of 6 subjects (1.8). Discussion & Conclusions: The majority of intubated patients on MV had both pepsin and salivary amylase in their sputum, likely due to microaspiration of secretions.; This finding suggests greater efforts are needed to reduce patients' risk. Ongoing strategies to prevent gastric reflux are important such as head of bed elevation and monitoring residuals. Presence of salivary amylase within tracheal secretions may indicate a need for more frequent oropharyngeal suctioning as part of routine care of intubated patients. Analysis shows no variations of the presence of pepsin or salivary amylase in relation to feeding tube placement or type of ETT. Generalizability is limited by the small sample size.

Milk allergens were digested by allowing them to flow through a chromatography column, where pepsin was conjugated to the stationary phase of the column. The allergen fragments were then characterized both biochemically, by using SDS-PAGE and gel permeation chromatography, and immunologically, by examining their reactivity to IgE and monoclonal antibodies.

Enzimas são proteínas utilizadas em processos tecnológicos diversos. Estas enzimas dependendo do tipo e grau de pureza são geralmente caras. Comumente as enzimas exigem controle contínuo do processo no que se refere à temperatura, pH, agitação, entre outros, e após o uso são descartadas, o que torna o custo do processo mais elevado. Em decorrência disto, a imobilização de enzimas em suportes insolúveis e inertes, vem sendo proposta com resultados promissores de manutenção e até mesmo aumento da atividade enzimática, resistência mecânica, térmica e de pH, bem como por apresentar maior facilidade de remoção da enzima do sistema e possibilitar sua reutilização. Por causa disto, diferentes tipos de suportes vêem sendo estudados, dentre estes, os materiais poliméricos, tem recebido atenção especial. A quitosana é um polímero natural, biocompatível, biodegradável e atóxico. É obtida de fontes renováveis provenientes do descarte de cascas de crustáceos da indústria de alimentos, o que constitui um fator ambiental importante atualmente. Neste trabalho a enzima pepsina foi imobilizada em membranas liofilizadas de quitosana e O-carboximetilquitosana reticuladas ou não com glutaraldeído. A pepsina imobilizada na membrana de quitosana reticulada com glutaraldeído manteve sua atividade enzimática e o suporte apresentou propriedades físico-químicas de resistência a solubilização em pH ácido, o qual é necessário para atividade da pepsina. O processo de liofilização preservou a estrutura do suporte e não comprometeu a atividade enzimática. Demonstrando que o processo de liofilização é viável para secagem e incorporação de enzimas. / Enzymes are proteins used in a wide variety of biotechnological processes. Commonly, enzymes require stringent conditions, such as a particular pH, temperature, stirring, etc. In chemical and biochemical reactions, purified enzymes can be rather costly and additionally, must be discarded after each use, which is still less economical. As a result of this, enzyme immobilization on insoluble and inert supports has been studied as a manner to overcome these problems and optimize enzymes use. Promising results of greater immobilized enzyme activity and stability over a broader range of pH and temperature have been reported. As well, immobilized enzymes can be easily removed from the system and reused. Various materials have been employed as enzymes supports, among then, the polymers have received special attention. Chitosan is a natural polymer that presents biocompatibility, biodegradability and nontoxicity. Chitosan is obtained from crustacean shell wastes discarded by the food industry, and recover this material constitutes an important environmental factor nowadays. In this work the enzyme pepsin was immobilized on freezedried chitosan and O-Carboxymethylchitosan membranes crosslinked or not with glutaraldehyde. Pepsin immobilized on chitosan membrane crosslinked with glutaraldehyde maintained its enzymatic activity and the polymer support provided physicochemical properties such resistance to dissolution in acid pH. Acid pH is required for pepsin activity. The freeze-drying process preserved the support structure and did not compromise the enzymatic activity. Demonstrating that, freeze drying process, is viable for drying and enzymes incorporation.

Tez (Tıpta Uzmanlık)--Süleyman Demirel Üniversitesi, Tıp Fakültesi, Kulak Burun Boğaz Anabilim Dalı, 2004. / Bibliyografya var.

Thesis (M.Sc. (Biochemistry))--Mahidol University, 1979.