Smith K, Borges A, Ariyanayagam M R, Fairlamb A H
Department of Medical Parasitology, London School of Hygiene and Tropical Medicine, U.K.
Biochem J. 1995 Dec 1;312 ( Pt 2)(Pt 2):465-9. doi: 10.1042/bj3120465.
Intracellular levels of glutathione and glutathionylspermidine conjugates have been measured throughout the growth phases of Escherichia coli. Glutathionylspermidine was present in mid-log-phase cells, and under stationary and anaerobic growth conditions accounted for 80% of the total glutathione content. N1,N8-bis(glutathionyl)spermidine (trypanothione) was undetectable under all growth conditions. The catalytic constant kcat/Km of recombinant E. coli glutathione reductase for glutathionylspermidine disulphide was approx. 11,000-fold lower than that for glutathione disulphide. The much higher catalytic constant for the mixed disulphide of glutathione and glutathionylspermidine (11% that of GSSG), suggests a possible explanation for the low turnover of trypanothione disulphide by E. coli glutathione reductase, given the apparent lack of a specific glutathionylspermidine disulphide reductase in E. coli.
在大肠杆菌的整个生长阶段，已对谷胱甘肽和谷胱甘肽亚精胺缀合物的细胞内水平进行了测定。谷胱甘肽亚精胺存在于对数中期的细胞中，在稳定期和厌氧生长条件下，其占总谷胱甘肽含量的80%。在所有生长条件下均未检测到N1,N8-双（谷胱甘肽基）亚精胺（锥虫硫醇）。重组大肠杆菌谷胱甘肽还原酶对谷胱甘肽亚精胺二硫化物的催化常数kcat/Km约比谷胱甘肽二硫化物低11,000倍。谷胱甘肽和谷胱甘肽亚精胺的混合二硫化物的催化常数要高得多（为谷胱甘肽二硫化物的11%），鉴于大肠杆菌中明显缺乏特异性的谷胱甘肽亚精胺二硫化物还原酶，这可能解释了大肠杆菌谷胱甘肽还原酶对锥虫硫醇二硫化物的低周转率。
