Asano Y, Nakazawa A, Kato Y, Kondo K
Sagami Chemical Research Center, Kanagawa, Japan.
J Biol Chem. 1989 Aug 25;264(24):14233-9.
A novel aminopeptidase active toward D-amino acid-containing peptides, D-amino acid amides, and D-amino acid esters has been purified 2,800-fold to homogeneity from a bacterium Ochrobactrum anthropi SCRC C1-38, which had been isolated from soil. The enzyme has a molecular weight of about 122,000 and is composed of two identical subunits (Mr = 59,000). The optimal pH for activity was 8.0. It showed strict D-stereospecificity toward substrates including low molecular weight D-amino acid amides such as D-alanine amide, D-alpha-aminobutyric acid amides, and D-serine amide; D-alanine N-alkylamides such as D-alanine-p-nitroanilide, D-alanine benzylamide, and D-alanine n-butylamide; and peptides with a D-alanine at the NH2 terminus such as D-alanylglycine, D-alanylglycylglycine, D-alanyl-L-alanyl-L-alanine, and D-alanine oligomers. Generally, the enzyme did not act on substrates composed of L-amino acid at the NH2 terminus, although it showed low stereospecificity only toward substrates such as the methyl esters of L-alanine, L-serine, and L-alanine-p-nitroanilide. Comparing the Km and Vmax values for the major substrates, it is clear that the enzyme prefers peptides to amino acid arylamides or amino acid amides. The enzyme was tentatively named as "D-aminopeptidase." EDTA and divalent cations have no effect on the enzyme activity. The enzyme appears to be a thiol peptidase.
一种对含D-氨基酸的肽、D-氨基酸酰胺和D-氨基酸酯具有活性的新型氨肽酶已从土壤中分离出的人苍白杆菌Ochrobactrum anthropi SCRC C1-38中纯化了2800倍，达到同质。该酶分子量约为122,000，由两个相同的亚基组成（Mr = 59,000）。活性的最适pH为8.0。它对包括低分子量D-氨基酸酰胺如D-丙氨酸酰胺、D-α-氨基丁酸酰胺和D-丝氨酸酰胺；D-丙氨酸N-烷基酰胺如D-丙氨酸对硝基苯胺、D-丙氨酸苄基酰胺和D-丙氨酸正丁酰胺；以及在NH2末端带有D-丙氨酸的肽如D-丙氨酰甘氨酸、D-丙氨酰甘氨酰甘氨酸、D-丙氨酰-L-丙氨酰-L-丙氨酸和D-丙氨酸低聚物等底物表现出严格的D-立体特异性。一般来说，该酶对NH2末端由L-氨基酸组成的底物无作用，尽管它仅对L-丙氨酸甲酯、L-丝氨酸甲酯和L-丙氨酸对硝基苯胺等底物表现出低立体特异性。比较主要底物的Km和Vmax值，很明显该酶更喜欢肽而不是氨基酸芳基酰胺或氨基酸酰胺。该酶暂定名为“D-氨肽酶”。EDTA和二价阳离子对酶活性无影响。该酶似乎是一种巯基肽酶。
