Purification, nucleotide sequence and some properties of a bifunctional isomerase/decarboxylase from the homoprotocatechuate degradative pathway of Escherichia coli C
作者:David I. ROPER、Ronald A. COOPER
DOI:10.1111/j.1432-1033.1993.tb18279.x
日期:1993.10
protein. Some kinetic properties of the purified isomerase/decarboxylase protein were investigated and it was shown that there is a 49,000-fold preference for 2-hydroxyhepta-2,4-diene-1,7-dioate over the structurally related compound 5-carboxymethyl-2-hydroxymuconate, the substrate of a second isomerase in the same catabolic pathway. Comparison of the amino acid sequences of the two isomerases showed
研究了从缺失亚克隆出现的,编码2-羟基庚-2,4-二烯-1,7-二酸酯异构酶和5-氧opent-3-烯-1,1,2,5-三羧酸酯脱羧酶的DNA的1.8-kbp区域进一步。通过核苷酸测序,发现编码M(r)44514的多肽的单个开放阅读框。缺失亚克隆之一以升高的水平表达脱羧酶和异构酶活性,并用于促进酶的纯化。两种活性共纯化,表明它们是同一蛋白质的不同活性。研究了纯化的异构酶/脱羧酶蛋白的一些动力学特性,结果表明,2-羟基庚-2,4-二烯-1,7-二酸酯相对于结构相关化合物5-羧甲基-2的优先级为49,000倍。 -羟基粘康酸酯 同一分解代谢途径中第二种异构酶的底物 两种异构酶的氨基酸序列的比较仅显示出低水平的相似性,表明这两种酶在进化上不相关。但是,异构酶/脱羧酶序列的N末端一半(残基1-202)与后半部分(残基203-406)的比较显示出显着相似性,这表明可能已经发生了重复以产生双功能基因。