Investigation of physiological functions of a 3-mercaptopyruvate sulfurtransferase

1.通过对人肝脏3-巯基丙酮酸硫转移酶(3-MST，EC2.8.1.2)的序列分析，确定了该酶的完整氨基酸结构。该酶由297个氨基酸残基组成，计算相对分子质量为33,176.7道尔顿。人3-MST与罗丹明的同源性为66.9%，推导的氨基酸序列同源性为59.7%。根据它们的全序列相似性，3-MST和罗丹尼斯被证实是进化上相关的酶。当3-MST基因在大肠杆菌和Cos7细胞中瞬时表达时，3-MST活性分别提高了20倍和45倍。从人胎肝cDNA文库中克隆了人硫代硫酸盐(氰化物硫代转移酶，EC 2.8.1.1)的全长基因。序列分析显示，该基因有一个开放阅读框，编码一个297个氨基酸残基的多肽，计算质量为33427道尔顿。当罗丹尼斯基因在大肠杆菌和Cos7细胞中瞬时表达时，活性分别提高了40倍和150倍。序列同源性分析表明，该基因与牛的同源性为89.6%，与大鼠的同源性为90.2%，与小鼠和中国仓鼠的同源性为91.2%，与禽类同源基因的同源性为71.4%，且在进化过程中高度保守。

1. A complete amino acid structure of human liver 3-mercaptopyruvate sulfurtransferase (3-MST,EC2.8.1.2) was determined by sequence analysis of cDNA and purified enzyme. The enzyme consists of 297-amino acid residues with a calculated molecular mass of 33,176.7daltons. Sequence identity in cDNA and the deduced amino acid sequence are 66.9 and 59,7% respectivity, between human 3-MST and rhodanese. By their entire sequence similarity 3-MST and rhodanese are confirmed to be evolutionarily related enzyme. When the 3-MST cDNA was transiently expressed in Escherchia coli and Cos7 cells, the 3-MST activity increased 20-fold and 45-fold, respectively.2. cDNA for the human rhodanese (thiosulfate ; cyanide sulfurtransuferase, EC 2.8.1.1) was cloned from a human fetal liver cDNA library. Sequencing of the cDNA revealed an open reading frame that encodes a 297-residue polypeptide with a calculated mass of 33427 daltons. When the rhodanese cDNA was transiently expressed in Escherchia coli and Cos7 cells, the rhodanese activity increased 40-fold and 150-fold, respectively. Sequence homology analysis showed that the human rhodanese is 89.6% identical to bovine, 90.2% identical to rat, 91.2% identical to mouse and Chinese hamster, and 71.4% similar to avian counterparts, respectively, and that rhodanese was highly conserved across evolution.