Abstract: A D-aminoacylase having a high substrate specificity is provided. This D-aminoacylase can produce D-amino acids from N-acetyl-D,L-amino acids conveniently and efficiently at a low cost. A D-aminoacylase produced by a microorganism of genus Defluvibacter; which acts on a N-acetyl-D-amino acid; which has a molecular weight (as determined by electrophoresis) of about 55,000 daltons, and an isoelectric point (as determined by two-dimensional electrophoresis for denatured system) of 5.3; which acts on N-acetyl-D-valine, N-acetyl-D-leucine, and the like, but not on N-acetyl-L-valine, N-acetyl-L-leucine, and the like; which has an optimal temperature of 37° C. (pH 8) and an optimal pH value of 8 to 8.5 at 37° C.; and whose activity is inhibited by Mn2+, Co2+, Ni2+, and Zn2+ each at 1 mmol/L, and by dithiothreitol, 2-mercaptoethanol, o-phenanthroline, and L-cysteine each at 5 mmol/L.

Abstract: A D-aminoacylase having a high substrate specificity is provided. This D-aminoacylase can produce D-amino acids from N-acetyl-D,L-amino acids conveniently and efficiently at a low cost. A D-aminoacylase produced by a microorganism of genus Defluvibacter; which acts on a N-acetyl-D-amino acid; which has a molecular weight (as determined by electrophoresis) of about 55,000 daltons, and an isoelectric point (as determined by two-dimensional electrophoresis for denatured system) of 5.3; which acts on N-acetyl-D-valine, N-acetyl-D-leucine, and the like, but not on N-acetyl-L-valine, N-acetyl-L-leucine, and the like; which has an optimal temperature of 37° C. (pH 8) and an optimal pH value of 8 to 8.5 at 37° C.; and whose activity is inhibited by Mn2+, Co2+, Ni2+, and Zn2+ each at 1 mmol/L, and by dithiothreitol, 2-mercaptoethanol, o-phenanthroline, and L-cysteine each at 5 mmol/L.

Abstract: The present invention provides a method for quantitatively determining homocysteine in a biological specimen containing homocysteine and cysteine by use of an enzyme which is capable of forming hydrogen sulfide both from homocysteine and from cysteine, which comprises (a) reacting the biological specimen with cysteine dioxygenase in the absence of a reducing agent, (b) subsequently reacting the resultant specimen of (a) with a reducing agent and the enzyme which is capable of forming hydrogen sulfide both from homocysteine and from cysteine, and (c) measuring the concentration of the hydrogen sulfide thus obtained to determine the homocysteine concentration in the biological specimen; and a reagent for such a quantitative determination of homocysteine.

Abstract: A D-aminoacylase having a high substrate specificity is provided. This D-aminoacylase can produce D-amino acids from N-acetyl-D,L-amino acids conveniently and efficiently at a low cost. A D-aminoacylase produced by a microorganism of genus Defluvibacter; which acts on a N-acetyl-D-amino acid; which has a molecular weight (as determined by electrophoresis) of about 55,000 daltons, and an isoelectric point (as determined by two-dimensional electrophoresis for denatured system) of 5.3; which acts on N-acetyl-D-valine, N-acetyl-D-leucine, and the like, but not on N-acetyl-L-valine, N-acetyl-L-leucine, and the like; which has an optimal temperature of 37° C. (pH 8) and an optimal pH value of 8 to 8.5 at 37° C.; and whose activity is inhibited by Mn2+, Co2+, Ni2+, and Zn2+ each at 1 mmol/L, and by dithiothreitol, 2-mercaptoethanol, o-phenanthroline, and L-cysteine each at 5 mmol/L.

Abstract: The present invention provides a method for quantitatively determining homocysteine in a biological specimen containing homocysteine and cysteine by use of an enzyme which is capable of forming hydrogen sulfide both from homocysteine and from cysteine, which comprises (a) reacting the biological specimen with cysteine dioxygenase in the absence of a reducing agent, (b) subsequently reacting the resultant specimen of (a) with a reducing agent and the enzyme which is capable of forming hydrogen sulfide both from homocysteine and from cysteine, and (c) measuring the concentration of the hydrogen sulfide thus obtained to determine the homocysteine concentration in the biological specimen; and a reagent for such a quantitative determination of homocysteine.