title: A mutant leucine aminopeptidase from Streptomyces cinnamoneus with enhanced L-aspartyl L-amino acid methyl ester synthetic activity.
abstract: L-aspartyl L-amino acid methyl ester was synthesized using a mutant of a thermostable leucine aminopeptidase from Streptomyces cinnamoneus, D198 K SSAP, obtained in previously. A peptide of high-intensity sweetener, L-aspartyl-L-phenylalanine methyl ester, was selected as a model for demonstrating the synthesis of L-aspartyl L-amino acid methyl ester. The hydrolytic activities of D198 K SSAP toward L-aspartyl-L-phenylalanine and its methyl ester were, respectively, 74-fold and fourfold higher than those of wild type. Similarly, the initial rate of the enzyme for L-aspartyl-L-phenylalanine methyl ester synthesis was over fivefold higher than that of wild-type SSAP in 90% methanol (v/v) in a one-pot reaction. Furthermore, other L-aspartyl L-amino acid methyl esters were synthesized efficiently using D198 K SSAP. Results show that the substitution of Asp198 of SSAP with Lys is effective for synthesizing L-aspartyl L-amino acid methyl ester.
authors.affiliation: Department of Agricultural, Biological, and Environmental Sciences, Faculty of Agriculture, Tottori University, Tottori, Japan. arima@muses.tottori-u.ac.jp
authors.forename: Jiro
authors.initials: J
authors.lastname: Arima
authors.forename: Mirai
authors.initials: M
authors.lastname: Kono
authors.forename: Manami
authors.initials: M
authors.lastname: Kita
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Mori
mesh_terms: D019943:Amino Acid Substitution; D001218:Aspartame / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D007931:Leucyl Aminopeptidase / Q000235:genetics* / Q000378:metabolism*; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics*
chemical_list: D050505:Mutant Proteins; D007931:Leucyl Aminopeptidase; D001218:Aspartame