Publications by authors named "Yasuko Kumaki"

Using soft granules consisting of Celite 535 and dried Aspergillus oryzae NBRC100959 mycelia containing β-fructofuranosidase as a whole-cell catalyst, N-acetylsucrosamine [β-D-fructofuranosyl-(2→1)-2-acetamido-2-deoxy-α-D-glucopyranoside] was produced from sucrose and 2-acetamido-2-deoxy-D-glucose by enzymatic transfructosylation. The isolated yield of N-acetylsucrosamine from the reaction mixture was 22.1% (from sucrose).

View Article and Find Full Text PDF

The chromosomal DNA of the syntrophic thermophile Symbiobacterium thermophilum contains open reading frames of the genes encoding family M42 aminopeptidases, Pep1079, Pep1080, and Pep1081. To characterize these peptidases, the genes were cloned into Escherichia coli and overexpressed. Our experiments using the recombinant proteins confirmed that Pep1079, Pep1080, and Pep1081 are components of arginyl or lysinyl aminopeptidases that require Co²+ for enzymatic activity.

View Article and Find Full Text PDF

Vibrio parahaemolyticus KN1699 produces 4-O-(N-acetyl-beta-d-glucosaminyl)-d-glucosamine (GlcNAc-GlcN) as a major end product from chitin using two extracellular hydrolases: glycoside hydrolase family 18 chitinase, which produces (GlcNAc)(2) from chitin, and carbohydrate esterase (CE) family 4 chitin oligosaccharide deacetylase (COD), which hydrolyzes the N-acetyl group at the reducing-end GlcNAc residue of (GlcNAc)(2). In this study, we clarified that this heterodisaccharide functions as an inducer of the production of the two above-mentioned chitinolytic enzymes, particularly chitinase. Similar results for chitinase production were obtained with other chitin-decomposing Vibrio strains harboring the CE family 4 COD gene; however, such an increase in chitinase production was not observed in chitinolytic Vibrio strains that did not harbor the COD gene.

View Article and Find Full Text PDF