title: Isolation of milk-clotting enzyme from transgenic sheep milk and its comparison with calf chymosin.
abstract: Technology for preparation of chymosin from milk of transgenic sheep has been elaborated. Purification of the preparation by ion-exchange chromatography on aminosilochrom and biospecific chromatography on bacitracin-Sepharose yielded homogeneous active enzyme. Hydrolysis of protein substrates (hemoglobin, BSA, and sodium caseinate) by the transgenic sheep chymosin and stability of the enzyme at various values of pH were studied. Judging by the amino acid composition, the N-terminal sequence involving six amino acid residues, molecular mass, stability at various pH values, and the catalytic activity against the protein substrates, the transgenic sheep chymosin is identical to calf chymosin.
authors.affiliation: Research and Production Animal Biotechnology Center, Poselok Gorki Leninskie, Moscow Region, 142712, Russia.
authors.forename: M N
authors.initials: MN
authors.lastname: Mezina
authors.forename: G I
authors.initials: GI
authors.lastname: Lavrenova
authors.forename: M I
authors.initials: MI
authors.lastname: Prokof'ev
authors.forename: V V
authors.initials: VV
authors.lastname: Starovoitova
authors.forename: V I
authors.initials: VI
authors.lastname: Ermolaev
authors.forename: V Y
authors.initials: VY
authors.lastname: Chernyh
authors.forename: G N
authors.initials: GN
authors.lastname: Balandina
authors.forename: S S
authors.initials: SS
authors.lastname: Demidovich
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D030801:Animals, Genetically Modified; D016282:Aspartic Acid Endopeptidases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D002417:Cattle; D002852:Chromatography, Ion Exchange / Q000379:methods; D012085:Chymosin / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D004586:Electrophoresis / Q000379:methods; D004789:Enzyme Activation / Q000502:physiology; D004795:Enzyme Stability / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D008892:Milk / Q000201:enzymology*; D012756:Sheep; D013045:Species Specificity; D013379:Substrate Specificity / Q000502:physiology
chemical_list: D000596:Amino Acids; D016282:Aspartic Acid Endopeptidases; C022517:rennin-like enzyme (Aspergillus ochraceus); D012085:Chymosin