中文摘要：

通过同源性分析，发现苜蓿中华根瘤茵（Sinorhizobium meliloti）菌株Rm1021中matB基因与三叶草生物型豌豆根瘤茵（Rhizobium leguminosarum by．trifolii）和慢生型大豆根瘤茵（Bradyrhizobium japonicum USDA110）中编码丙二酸单酰辅酶A合成酶（malonyl-CoA synthetase）基因在氨基酸水平上分别达到了75％和67％一致性，具有高度同源性。因此，从Rml021中克隆出matB基因，并在大肠埃希菌（Escherichiacoli）中进行体外诱导表达和纯化。纯化的MatB蛋白具有丙二酸单酰辅酶A合成酶的活性，测定的Km值是710μmol，Vmax是0．209μmol／min／mg。

英文摘要：

Based on the analysis of amino acids homology, we found that matB gene in Sinorhizobium meliloti Rml021 show highly homology with the malonyl-CoA synthetase of the Rhizobium leguminosarum by. trifolii and the Bradyrhizobium japonicttm USDA 110. The MatB protein shares 75% and 67% indentity with malonyl-CoA synthetase of the R. leguminosarum by. trifolii and the B. japonicurn USDA I I0, respectively. So we cloned matB gene, constructed the matB recombinant plasmid and purified it from E. coll. We found that the purified MatB have the activity of malonyl-CoA synthetase, showing that its Kin value is 710 μmol and Vmax is 0. 209 μxmol/min/mg.