Veĭko V P, Siprashvili Z Z, Ratmanova K I, Gul'ko L B
Bioorg Khim. 1995 Nov;21(11):834-7.
Using site-directed mutagenesis, mutant genes of the E.coli UDPase that coded proteins with point substitutions of histidine residues (i.e., H8N, H47N, H101N, H122N, H152N, H179N, and H240N) were constructed. Study of the enzymatic activity of mutant UDPases showed that histidine-asparagine substitutions at the positions 47, 101, 152, 179, and 240 do not affect protein functioning. Whereas H122N and H8N substitutions inhibit the activity of UDPase by 60 and 100%, respectively. This evidences the important functional role of the His122 and His8 residues for the formation of the active site fo the enzyme.
利用定点诱变技术构建了大肠杆菌UDP酶的突变基因，这些突变基因编码的蛋白质中组氨酸残基发生了点突变（即H8N、H47N、H101N、H122N、H152N、H179N和H240N）。对突变型UDP酶的酶活性研究表明，47、101、152、179和240位的组氨酸-天冬酰胺替换不影响蛋白质功能。而H122N和H8N替换分别使UDP酶活性抑制60%和100%。这证明了His122和His8残基对酶活性位点形成具有重要的功能作用。
