title: Purification and characterization of pregastric esterase from calf.
abstract: Calf pregastric esterase (PGE) was purified from calf gullet tissues. The tissue was excised and lyophilized, and lipid materials were extracted with acetone and n-butanol at -20 degrees C. Proteins were extracted from the delipidated tissue with a buffer containing a chaotropic salt (NaSCN) to solubilize hydrophobically bound protein aggregates. Calf PGE precipitated from the crude extract at pH 5.0. The precipitated, solubilized proteins were subjected to anion-exchange chromatography on DEAE-Sephacel, and the enzymatic activity was eluted using a linear gradient from 0.10 to 0.50 M NaCl at pH 8.0. Fractions with high specific activities were then chromatographed twice using gel filtration on Sephadex G-100. The resultant enzyme was shown to be pure upon discontinuous electrophoresis in 12% polyacrylamide containing 0.1% sodium dodecyl sulfate (SDS-PAGE). From SDS-PAGE gel patterns, a molecular weight of 49,000 was determined. The amino acid composition of the enzyme allowed calculation of an "average hydrophobicity" (Bigelow index) of 1150 cal/residue. This indicates that calf PGE is relatively hydrophobic, being similar to proteins such as alpha-lactalbumin and bovine serum albumin in average hydrophobicity.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D004947:Esophagus / Q000201:enzymology*; D008049:Lipase / Q000302:isolation & purification*; D008970:Molecular Weight; D012997:Solvents
chemical_list: D000596:Amino Acids; D012997:Solvents; D008049:Lipase; C043101:gastric triacylglycerol lipase