Schroeder U, Henrich B, Fink J, Plapp R
Universität Kaiserslautern, Abteilung Mikrobiologie, FRG.
FEMS Microbiol Lett. 1994 Oct 15;123(1-2):153-9. doi: 10.1111/j.1574-6968.1994.tb07215.x.
Peptidase D of Escherichia coli was overproduced from a multicopy plasmid and purified to electrophoretic homogeneity. The pure enzyme was stable at 4 degrees C or -20 degrees C and had a pH optimum at pH 9, and a pI of 4.7; the temperature optimum was at 37 degrees C. As the enzyme was activated by Co2+ and Zn2+, and deactivated by metal chelators, it appears to be a metallopeptidase. By activity staining of native gels, 11 dipeptides which are preferentially cleaved by peptidase D were identified. Peptidase D activity required dipeptide substrates with an unblocked amino terminus and the amino group in the alpha or beta position. Non-protein amino acids and proline were not accepted in the C-terminal position, whereas some dipeptide amides and formyl amino acids were hydrolyzed. Km values of 2 to 5 mM indicate a relatively poor interaction of the enzyme with its substrates.
大肠杆菌的肽酶D通过多拷贝质粒过量表达，并纯化至电泳纯。纯酶在4℃或-20℃下稳定，最适pH为9，pI为4.7；最适温度为37℃。由于该酶被Co2+和Zn2+激活，并被金属螯合剂失活，它似乎是一种金属肽酶。通过对天然凝胶的活性染色，鉴定出11种优先被肽酶D切割的二肽。肽酶D的活性需要具有未封闭氨基末端且氨基位于α或β位的二肽底物。非蛋白质氨基酸和脯氨酸不被接受在C末端位置，而一些二肽酰胺和甲酰基氨基酸可被水解。2至5 mM的Km值表明该酶与其底物的相互作用相对较弱。
