Purification and characterization of pancreatic elastase from Atlantic cod (Gadus morhua)

Chemically modified alginate bead matrix for efficient adsorptive recovery of trypsin from fresh bovine pancreas

The adsorption of commercial trypsin (Try) onto epichlorohydrin cross-linked alginate-guar gum matrix has been studied at equilibrium in batch and in fixed bed column. Experiments were conducted to study the effect of ionic strength, temperature and to obtain a thermodynamic characterization of the adsorption process. The resulting adsorption isotherm fitted the Hill equation. Experimental breakthrough curve profiles were compared with the theoretical breakthrough profiles obtained from the mathematical model, bed depth service time. At pH 5.0, 1.0 g hydrated matrix adsorbed 480.0 milligram of Try per gram of dried bed. The desorption process showed 80% of Try recovery in 50 mM phosphate buffer, pH 7.00-500 mM NaCl-20% propylene glycol. The obtained results were applied to an adsorption/washing/desorption process with fresh pancreas homogenate yielded 20% of recovery and 5.7 purification factor of Try. The matrix remained functional until the fifth cycle of repeated batch enzyme adsorption. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018.

Atlantic cod trypsin-catalyzed peptide synthesis with inverse substrates as acyl donor components

Atlantic cod trypsin-catalyzed peptide synthesis has been studied by using p-amidino- and p-guanidinophenyl esters of N-(tert-butyloxycarbonyl)amino acid as acyl donor components. The reaction temperature was optimized at 0 degrees C. The method was shown to be successful as effectively for synthesizing the peptide and useful for preparing dipeptide between D-amino acid with D-amino acid and beta-amino acid with beta-amino acid, respectively. The enzymatic hydrolysis of the resulting products was negligible.

Extraction of trypsin from bovine pancreas by applying polyethyleneglycol/sodium citrate aqueous two-phase systems

The goal of this work was to determine the optimal conditions for separating trypsin (TRP) from alpha-chymotrypsin (ChTRP) and to apply them for trypsin purification from bovine pancreas by liquid-liquid extraction with polyethyleneglycol/sodium citrate (PEG/NaCit) aqueous two-phase systems. Partitioning behaviours of TRP and ChTRP are demonstrated to be very sensitive to variables such as PEG molecular weight, pH and tie line length. Aqueous two-phase systems (ATPSs) formed by PEG of MW 3350 and NaCit pH 5.20 showed the best separation capability. The addition of NaCl up to a final concentration of 7% (w/w) and the decrease of top/bottom volume ratio to 0.1 led to the recovery of 60% of pancreatic TRP in a concentrated form in the top phase with a 3-fold purification. Biomass presence up to 25% (w/w) of the total system mass did not affect significantly yield and purification parameters.

Partitioning features of bovine trypsin and α-chymotrypsin in polyethyleneglycol-sodium citrate aqueous two-phase systems

The partitioning of bovine trypsin and alpha-chymotrypsin--proteases of similar physico-chemical properties--in different polyethyleneglycol/sodium citrate aqueous two-phase systems was investigated. The effect of different factors such as polyethyleneglycol molecular weight, pH, tie line length, temperature and the presence of an inorganic salt on the protein partition coefficient were analysed. Both a decrease in PEG molecular weight and an increase in pH led to a higher partition coefficient for both enzymes. Aqueous two-phase systems formed by PEG of molecular weight 3350 and citrate pH 5.2 showed the best separation capability which was enhanced in presence of sodium chloride 3%. The transfer of both proteins to the top phase was associated with negative enthalpic and entropic changes.

Cathepsin D from Atlantic cod (Gadus morhua L.) liver. Isolation and comparative studies

The isolated cathepsin D-like enzyme from Atlantic cod (Gadus morhua L.) liver was shown to be a monomer with a molecular mass of approximately 40 kDa. It was inhibited by Pepstatin A and had an optimum for degradation of haemoglobin at pH 3.0. The purified enzyme had lower temperature stability than bovine cathepsin D. Antibodies raised against the purified enzyme and against two C-terminal peptides of cod cathepsin D recognized a 40 kDa protein in immunoblotting of the samples from the purification process. Both antisera showed cross reactivity with a similar sized protein in liver from cod, saithe (Pollachius virens L.), Atlantic herring (Clupea harengus L.) and Atlantic salmon (Salmo salar L.). A protein of same size was detected in wolffish (Anarhichas lupus L.) liver with the antibody directed against the purified enzyme. This antibody also recognized the native enzyme and detected the presence of cathepsin D in muscle of cod, saithe, herring and salmon. These antibodies may be useful in understanding the mechanisms of post mortem muscle degradation in fish by comparing immunohistochemical localization and enzyme activity, in particular in cod with different rate of muscle degradation. They may also be used for comparing muscle degradation in different fish species.

Aberrant localization of intracellular organelles, Ca2+ signaling, and exocytosis in Mist1 null mice

Ca2+ signaling and exocytosis are highly polarized functions of pancreatic acinar cells. The role of cellular architecture in these activities and the capacity of animals to tolerate aberrant acinar cell function are not known. A key regulator of acinar cell polarity is Mist1, a basic helix-loop-helix transcription factor. Ca2+ signaling and amylase release were examined in pancreatic acini of wild type and Mist1 null mice to gain insight into the importance of cellular architecture for Ca2+ signaling and regulated exocytosis. Mist1-/- acinar cells exhibited dramatically altered Ca2+ signaling with up-regulation of the cholecystokinin receptor but minimal effect upon expression of the M3 receptor. However, stimulation of inositol 1,4,5-trisphosphate production by cholecystokinin and carbachol was inefficient in Mist1-/- cells. Although agonist stimulation of Mist1-/- cells evoked a Ca2+ signal, often the Ca2+ increase was not in the form of typical Ca2+ oscillations but rather in the form of a peak/plateau-type response. Mist1-/- cells also displayed distorted apical-to-basal Ca2+ waves. The aberrant Ca2+ signaling was associated with mislocalization and reduced Ca2+ uptake by the mitochondria of stimulated Mist1-/- cells. Deletion of Mist1 also led to mislocalization of the Golgi apparatus and markedly reduced digestive enzyme content. The combination of aberrant Ca2+ signaling and reduced digestive enzyme content resulted in poor secretion of digestive enzymes. Yet, food consumption and growth of Mist1-/- mice were normal for at least 32 weeks. These findings reveal that Mist1 is critical to normal organelle localization in exocrine cells and highlight the critical importance of maintaining cellular architecture and polarized localization of cellular organelles in generating a propagating apical-to-basal Ca2+ wave. The studies also reveal the spare capacity of the exocrine pancreas that allows normal growth and development in the face of compromised exocrine pancreatic function.

A functional comparison of ovine and porcine trypsins

Trypsin was isolated from ovine and porcine pancreas using affinity chromatography on immobilized p-aminobenzamidine. Molecular masses of the two proteins were 23900 and 23435 Da, determined by matrix-assisted laser desorption/ionisation time of flight (MALDI-TOF) mass spectrometry. The purified trypsins were compared using the kinetic properties K(m) and k(cat) which were determined at pH 8.0 and between 25 and 55 degrees C. Comparison of the Michaelis constants for ovine and porcine trypsins toward N-alpha-benzoyl-arginine-p-nitroanilide (BapNA) indicated that ovine trypsin had higher affinity for this substrate than the porcine enzyme. The rates of the reactions catalysed by the two enzymes correlated strongly over the range of temperatures and substrate concentrations tested, as did the k(cat) values. The specific activity of ovine trypsin for BapNA was, on average, approximately 10% higher than that of the porcine enzyme over the range of conditions tested. Porcine trypsin was less susceptible to denaturation at low pH or high temperature than was ovine trypsin. Porcine and ovine trypsin produced seven identically sized fragments from auto-catalytic hydrolysis. Proposed regions of identity between ovine and porcine trypsins were I(54)-K(77), L(98)-R(107), S(134)-K(178) and N(209)-K(116). Hydrolysis of beta-lactoglobulin, egg white lysozyme or casein by ovine or porcine trypsin yielded virtually identical patterns of fragments although the rate at which fragments were produced, in the case of beta-lactoglobulin, differed between the two enzymes. On balance the two enzymes appear to be functionally identical in their action.

Kinetic and structural properties of two isoforms of trypsin isolated from the viscera of Japanese anchovy, Engraulis japonicus

Two isoforms of anchovy trypsin (aT-I and aT-II) were purified from the visceral extracts by (NH4)2SO4 fractionation followed by affinity chromatography, gel filtration, and ion-exchange chromatography. The homogeneity of the purified preparation was evidenced by both native- and SDS-PAGE, and further by gelatin zymography. Identities of aT-I and aT-II as trypsins were established by N-terminal amino acid sequencing, which matched exactly to the corresponding stretches of their respective amino acid sequences obtained by molecular cloning [Ahsan et al. (2000), Marine Biotechnol., in press]. Both isoforms were completely inhibited by serine protease inhibitors as well as by specific trypsin inhibitors. The purified anchovy trypsins showed considerably higher catalytic efficiencies (kcat/Km) than bovine trypsin as measured toward benzoyl-arginine p-nitroanilide (BAPA) and benzoyl-arginine ethyl ester (BAEE) at 25 degrees C; in particular, aT-II was 35 times more efficient than its mammalian counterpart against BAPA. This was due mainly to a dramatic decrease of Km values for anchovy trypsins, which are indicative of an evolutionary response toward increased substrate binding at suboptimal temperatures in the marine environment.