Stelkes-Ritter U, Wyzgol K, Kula M R
Institut für Enzymtechnologie Heinrich-Heine-Universität, Düsseldorf, Jülich, Germany.
Appl Microbiol Biotechnol. 1995 Dec;44(3-4):393-8. doi: 10.1007/BF00169934.
A microbial peptide amidase was found in a limited screening and purified about 500-fold from Stenotrophomonas maltophilia. The native enzyme has a molecular mass of 38 kDa (gel filtration). The sequence of the first 16 amino acids was determined by Edman degradation. The isoelectric point was found to be around 5.8. The peptide amidase exhibited a pH optimum of 6.0 and a temperature optimum of about 39-45 degrees C. The enzyme is stable in 50 mM TRIS/HCl, pH 7.5, at 30 degrees C, and the residual activity was found to be above 90% after 1 week of incubation. The biocatalyst is not inhibited by potential inhibitors like Hg2+, EDTA, D-cycloserine or dithiothreitol and only weakly influenced by inhibitors of serine proteases. The peptide amidase deamidates selectively C-terminal amide groups in peptide amides without hydrolysing internal peptide bonds or amide functions in the side-chain of glutamine or asparagine. Unprotected amino acid amides are not hydrolysed. The enzyme is stereoselective with regard to L-enantiomers in the C-terminal position.
在一次有限的筛选中发现了一种微生物肽酰胺酶，并从嗜麦芽窄食单胞菌中纯化了约500倍。天然酶的分子量为38 kDa（凝胶过滤法）。通过埃德曼降解法测定了前16个氨基酸的序列。发现其等电点约为5.8。该肽酰胺酶的最适pH为6.0，最适温度约为39-45℃。该酶在30℃的50 mM TRIS/HCl（pH 7.5）中稳定，孵育1周后残余活性高于90%。该生物催化剂不受Hg2+、EDTA、D-环丝氨酸或二硫苏糖醇等潜在抑制剂的抑制，仅受丝氨酸蛋白酶抑制剂的微弱影响。该肽酰胺酶选择性地使肽酰胺中的C端酰胺基脱酰胺，而不水解内部肽键或谷氨酰胺或天冬酰胺侧链中的酰胺官能团。未保护的氨基酸酰胺不被水解。该酶对C端位置的L-对映体具有立体选择性。
