title: PsoP1, a milk-clotting aspartic peptidase from the basidiomycete fungus Piptoporus soloniensis.
abstract: The first enzyme of the basidiomycete Piptoporus soloniensis, a peptidase (PsoP1), was characterized after isolation from submerged cultures, purification by fractional precipitation, and preparative native-polyarylamide gel electrophoresis (PAGE). The native molecular mass of PsoP1 was 38 kDa with an isoelectric point of 3.9. Similar to chymosin from milk calves, PsoP1 showed a maximum milk-clotting activity (MCA) at 35-40 °C and was most stable at pH 6 and below 40 °C. The complete inhibition by pepstatin A identified this enzyme as an aspartic peptidase. Electrospray ionization-tandem MS showed an amino acid partial sequence that was more homologous to mammalian milk clotting peptidases than to the chymosin substitute from a fungal species, such as the Zygomycete Mucor miehei. According to sodium dodecyl sulfate-PAGE patterns, the peptidase cleaved κ-casein in a way similar to chymosin and hydrolyzed β-casein slowly, as it would be expected from an efficient chymosin substitute.
authors: Zentrum Angewandte Chemie, Institut für Lebensmittelchemie der Gottfried Wilhelm Leibniz Universität Hannover, Callinstrasse 5, D-30167 Hannover, Germany.
authors: Hassan Abd
authors: HA
authors: El-Baky
authors: Diana
authors: D
authors: Linke
authors: Manfred
authors: M
authors: Nimtz
authors: Ralf Günter
authors: RG
authors: Berger
mesh_terms: D000818:Animals; D057055:Aspartic Acid Proteases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D001487:Basidiomycota / Q000201:enzymology*; D002364:Caseins / Q000378:metabolism; D008892:Milk / Q000378:metabolism*; D010447:Peptide Hydrolases; D013379:Substrate Specificity
chemical_list: D002364:Caseins; D057055:Aspartic Acid Proteases; D010447:Peptide Hydrolases