Purification and characterization of lamb pregastric lipase

Calf Pregastric Esterase Catalyzed Hydrolysis of 4-Nitrophenylalkanoates: pH and Temperature Effects

A commercial extract from the tongue and epiglottal region of suckling calf was partially purified to yield a calf pregastric enzyme with esterase activity against 4-nitrophenylalkanoate esters (C2-C12) at 370C, pH 7.2. The Km against 4-nitrophenylacetate was 0.023 mM, however, when 4-nitro-phenyldodecanoate was used as the substrate, the Km was 1.06 AM. The maximum activity was achieved at ca. 1.6 AM, which is similar to its critical micelle concentration. The reactivity is dependent upon pH. A pK of 7.23 which was obtained in the pH range 5.5-9.0 is indicative of a single ionizable residue. The activity dependence upon temperature of the partially purified enzyme was determined within the range of 25°C to 48°C and Eyring parameters were calculated.

Lamb Pregastric Lipase Activity: Catalyzed Hydrolysis of Dibutyryl-1,2(3)-Propanediols and Butyryl-1(2)-Propanol and Inhibition of the Catalyzed Hydrolysis of Tributyrylglycerol in the Presence of EDTA, LiCl, NaCl and Ethanol

Partially purified lamb pregastric lipase, LPGL, isolated from the tongue and epiglottal region of lamb, was used to catalyze the hydrolysis of tributyrylglycerol, the dibutyryl esters of propanediol and the butyryl esters of propanol at pH 6.5, 35°C. The relative rates of hydrolysis for tributyrylglycerol: dibutyryl-1,2-propanediol: dibutyryl-1,3-propanediol: butyryl-1-propanol: butyryl-2-propanol were 100: 35.4: 12.5: 4.1: 1.1, respectively. Monohydrolysis stoichiometry was observed for tributyrylglycerol and the diesters with saturation kinetics. In contrast, hydrolysis of the monoesters was first-order in substrate. The catalyzed hydrolysis of tributyrylglycerol was ~20% inhibited in the presence of 100 mM EDTA, 10% and 60% in the presence of 1 M NaCl and LiCl, respectively, and ~30% in 10% v/v ethanol.

Purification and Characterization of a Pregastric Esterase From a Hygienized Kid Rennet Paste

Rennet pastes obtained by maceration of gastric tissues from suckling kids are used traditionally to produce some artisanal cheeses in Spain. Besides milk-clotting function, rennet pastes provide proteolytic activity and lipolytic system, essentially pregastric, necessary in the development of piquant flavor typical of these cheeses. A simple and reproducible procedure allows us to obtain a standardized rennet paste that posses the desired activity and is of good microbiological quality. Concomitantly, a kid pregastric esterase (KPGE) was purified to homogeneity. The purification procedure was based on an aqueous extract of hygienized rennet paste (HRP), which was chromatographed on DEAE-Sepharose Fast Flow then adsorbed on phenyl superose followed by a re-chromatography on the same column. The final enzymatic preparation, where the overall activity recovery was 3%, showed a molecular mass of 53 kDa. The highest activity was determined on p-nitrophenyl butyrate, but marked hydrolysis was also detected on beta-naphthyl caprylate. In contrast, low activity on tributyrin (substrate under emulsion form) was detected, thus confirming the esterase character of purified enzyme.

Production of lipolyzed butteroil by a calf pregastric esterase immobilized in a hollow fiber reactor: III. Effect of glycerol

Lipolysis of butter oil in a hollow fiber reactor containing an immobilized calf pregastric esterase was studied at 40 degrees C, a pH of 6.0, and glycerol concentrations of 0, 150, and 500 g/L in the buffer solution. The concentrations of 10 fatty acid species in the lipolyzed product were determined using high-performance liquid chromatography. The rate of loss of enzyme activity and the relative selectivities of this esterase depended on the glycerol concentration. By contrast, the overall rate of release of fatty acids was not affected by the glycerol concentration. Loss of enzyme activity was modeled using first-order kinetics. The models for deactivation and reaction kinetics were fit simultaneously to the data. The model was successful in describing the rates of release of all 10 fatty acid species for a range of space times from 0 to 25 h. The parameters of the model were tested for dependence on glycerol concentration.

Lipolysis of butter oil by immobilized lamb pregastric esterase: I. Uniresponse kinetics-pH and temperature effects

Lamb pregastric esterase, immobilized by physical adsorption on microporous polypropylene in a hollow fiber reactor, has been employed to effect the continuous hydrolysis of the triglycerides in butter oil. Experimental data were obtained at temperatures from 35 to 45 degrees C and pH values from 5.5 to 6.5. The overall rate of hydrolysis was fastest at 40 degrees C and a pH of 6.0. Nonlinear regression methods were employed to determine the kinetic parameters of rate expressions based on a generic Ping-Pong Bi Bi mechanism. The best nonlinear fit of the data was consistent with a mechanism that assumes that acylation of the enzyme is the rate-limiting step in the hydrolysis reaction.

Effect of pH on the production of lipolyzed butter oil by a calf pregastric esterase immobilized in a hollow-fiber reactor: II. Multiresponse kinetics

The lipolysis of butter oil in a hollow-fiber reactor containing an immobilized calf pregastric esterase was studied at 40 degrees C and at pH values of 4.0, 5.0, 6.0, and 7.0. The concentrations of ten fatty acid species in the lipolyzed product were determined using high-performance liquid chromatography (HPLC). The relative specificity of this esterase depended on pH. Three mathematical models derived from a generalized Michaelis-Menten mechanism were tested for their ability to describe the rates of release of individual specific fatty acids. Loss of enzyme activity was modeled using first order kinetics. The models for deactivation and reaction kinetics were fit simultaneously to the data. The parameters of the model were also tested for dependence on pH. The model was successful in describing the rates of release of all ten fatty acid species for a range of space times and pH values.

Effect of pH on the production of lipolyzed butter oil by a calf pregastric esterase immobilized in a hollow-fiber reactor: I. uniresponse kinetics

A calf pregastric esterase immobilized in a hollow-fiber reactor was employed to hydrolyze milkfat, thereby producing a lipolyzed butteroil. The reaction kinetics can be modeled by a two-parameter model of the general Michaelis-Menten form based on a ping-pong bi-bi mechanism; the rate of enzyme deactivation can be modeled as a first-order reaction. The initial concentration of accessible glyceride bonds, [G](O), was estimated by complete saponification of the substrate butteroil as 2400 mM. An extra sum of squares test indicated that not only the parameters of the kinetic generalized Michaelis-Menten model, but also the deactivation-rate constant varied significantly with pH. The optimum pH, for lypolysis is near 6.0 at a temperature of 40 degrees C because at this pH the rate of deactivation of the esterase is minimized.

Hydrolysis characteristics of bovine milk fat and monoacid triglycerides mediated by pregastric lipase from goats and kids

Commercial extracts from oro-pharyngeal tissues of goats and kids have been used as the source of pregastric lipase and have been processed to yield partially purified samples of the primary pregastric lipase. The activity of these lipases against tributyrylglycerol has been determined over a range of pH and temperatures. Optimum pH conditions for pregastric lipase ranged from pH 5.6 to 6.5 for goats and from pH 5.5 to 6.2 for kids, respectively; the optimum temperature ranged from 43 to 60 degrees C. Optima for kid lipase extended slightly below pH 5.5 and higher than 60 degrees C; which were the limits of the test conditions. The enzymes were also used as catalysts for the hydrolysis of monoacid triglycerides (C4:0 to C12:0) at 40 degrees C and pH 6.5; activity was maximum against tributyrylglycerol (C4:0). Values for the Michaelis-Menten constant, increased as carbon chain length of the carboxylic moiety on the triglycerides increased, but values were identical for pregastric lipases of both goats and kids. Anhydrous milk fat was hydrolyzed by the commercial extracts of pregastric lipases of goats and kids, and the resulting profiles for free fatty acids were very similar to one another and to the corresponding profile for a commercial sample of Parmesan cheese. There appear to be no significant differences in activity between the enzyme preparations from goats and kids.

Purification and molecular characterization of lamb pregastric lipase

Lamb pregastric lipase (LPGL) was purified from pharyngeal tissues. The purification procedure was based on an aqueous extract containing 0.7% Tween 80 which was chromatographed on DEAE-cellulose anion-exchanger and adsorbed on HA-Ultrogel followed by gel filtration on Ultrogel AcA-54. The final enzymatic preparation, where the overall activity recovery was 3%, showed a single protein band on SDS-PAGE with a molecular mass of 50 kDa. LPGL is a glycoprotein containing approx. 14% (w/w) of carbohydrate. Extensive deglycosylation using peptide N-glycosidase F yielded a protein with an apparent molecular mass of 43 kDa. An uncontrolled proteolysis of LPGL during the purification lead to a 45 kDa form which was previously observed in human lysosomal acid lipase (HLAL) and rabbit gastric lipase (RGL). The labile bond X54-Leu55 was identified. Isoelectric focusing of LPGL reveals a major band corresponding to an isoelectric point of 4.8. The pure enzyme displayed specific activities of 950 U mg-1, 300 U mg-1 and 30 U mg-1 at pH 6.0, using tributyroylglycerol, trioctanoylglycerol and trioleoylglycerol as substrates, respectively. Using Western blot analysis, a cross-immunoreactivity of LPGL was observed with purified anti-human gastric lipase polyclonal antibodies. Determination of the amino-acid sequence of 62 residues revealed a high degree of homology with other known preduodenal lipases.