title: Involvement of glutamine-238 in the substrate specificity of human laeverin/aminopeptidase Q.
abstract: Human laeverin/aminopeptidase Q (APQ) is a novel member of the M1 family of zinc aminopeptidases and is specifically expressed on the cell surface of extravillous trophoblasts. In this study, we examined the significance of Gln-238 of laeverin/APQ, a putative S1 site residue, by site-directed mutagenesis for its enzymatic activity and substrate specificity. Replacement of Gln-238 with Ala caused a significant change in substrate specificity rather than a decrease in enzymatic activity. These results indicate that Gln-238 is important for the substrate specificity of laeverin/APQ. In addition, our data suggest that direct electrostatic interaction between substrate and S1 site of the enzyme is not involved in the mutant enzyme's preference for basic amino acids.
authors.affiliation: Laboratory of Cellular Biochemistry, RIKEN, Wako, Saitama 351–0198, Japan.
authors.forename: Yoshikuni
authors.initials: Y
authors.lastname: Goto
authors.forename: Rina
authors.initials: R
authors.lastname: Yoshioka
authors.forename: Naomi
authors.initials: N
authors.lastname: Arisaka
authors.forename: Akira
authors.initials: A
authors.lastname: Hattori
authors.forename: Masafumi
authors.initials: M
authors.lastname: Tsujimoto
mesh_terms: D000409:Alanine; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D005973:Glutamine / Q000737:chemistry*; D006801:Humans; D045726:Metalloproteases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D013379:Substrate Specificity
chemical_list: D005973:Glutamine; C482089:LVRN protein, human; D045726:Metalloproteases; D000409:Alanine