title: Molecular and enzymatic properties of an aspartic proteinase from Rhizopus hangchow.
abstract: An aspartic proteinase, rhizopuspepsin (EC 3.4.23.21), from Rhizopus hangchow was purified. The M(r) and isoelectric point were determined as ca 37,000 and 4.5, respectively. The first 19 amino acids in the N-terminal region were SGSGVVPMTDYEYDIEYYG. The contents of the alpha-helix, beta-structure and random coil were calculated to be ca 7.5, 88.9 and 2.7%, respectively. The enzyme can activate trypsinogen at pH 3.0. The activity was completely inactivated by pepstatin A. The specificity and mode of action of the enzyme were investigated with oxidized insulin B-chain at pH 3. The enzyme hydrolysed primarily two peptide bonds, the Leu15-Tyr16 bond and the Tyr16-Leu17 bond, while additional cleavage of the bonds, Ala14-Leu15 and Phe24-Phe25 was also noted.
authors.affiliation: Department of Applied Biological Chemistry, Faculty of Agriculture, Tohoku University, Sendai, Japan.
authors.forename: E
authors.initials: E
authors.lastname: Ichishima
authors.forename: M
authors.initials: M
authors.lastname: Ojima
authors.forename: Y
authors.initials: Y
authors.lastname: Yamagata
authors.forename: S
authors.initials: S
authors.lastname: Hanzawa
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D000595:Amino Acid Sequence; D016282:Aspartic Acid Endopeptidases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D017433:Protein Structure, Secondary; D012233:Rhizopus / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D010446:Peptide Fragments; D016282:Aspartic Acid Endopeptidases