Department of Biochemistry, Faculty of Biological Science, Tarbiat Modares University, Tehran, Iran.
Appl Biochem Biotechnol. 2010 Nov;162(6):1519-28. doi: 10.1007/s12010-010-8933-0. Epub 2010 Apr 25.
A gene encoding methylglyoxal synthase from Thermus sp. GH5 (TMGS) was cloned, sequenced, overexpressed, and purified by Q-Sepharose. The TMGS gene was composed of 399 bp which encoded a polypeptide of 132 amino acids with a molecular mass of 14.3 kDa. The K (m) and k (cat) values of TMGS were 0.56 mM and 325 (s(-1)), respectively. The enzyme exhibited its optimum activity at pH 6 and 75 degrees C. Comparing the amino acid sequences and Hill coefficients of Escherichia coli MGS and TMGS revealed that the loss of Arg 150 in TMGS has caused a decrease in the cooperativity between the enzyme subunits in the presence of phosphate as an allosteric inhibitor. Gel filtration experiments showed that TMGS is a hexameric enzyme, and its quaternary structure did not change in the presence of phosphate.
从 Thermus sp. GH5 (TMGS) 中克隆、测序、过表达并通过 Q-Sepharose 纯化了编码甲基乙二醛合酶的基因。TMGS 基因由 399bp 组成，编码一个由 132 个氨基酸组成的多肽，分子量为 14.3kDa。TMGS 的 K (m) 和 k (cat) 值分别为 0.56mM 和 325(s(-1))。该酶在 pH6 和 75°C 下表现出最佳活性。比较大肠杆菌 MGS 和 TMGS 的氨基酸序列和 Hill 系数表明，TMGS 中 Arg150 的缺失导致在磷酸盐作为变构抑制剂存在下酶亚基之间的协同作用降低。凝胶过滤实验表明 TMGS 是一种六聚体酶，其四级结构在磷酸盐存在下没有改变。
