GLUTATHIONYLSPERMIDINE METABOLISM IN ESCHERICHIA-COLI

Intracellular levels of glutathione and glutathionylspermidine conjuga tes have been measured throughout the growth phases of Escherichia col i. Glutathionylspermidine was present in mid-log-phase cells, and unde r stationary and anaerobic growth conditions accounted for 80% of the total glutathione content. N-1,N-8-bis(glutathionyl)spermidine (trypan othione) was undetectable under all growth conditions. The catalytic c onstant k(cat)/K-m of recombinant E. coli glutathione reductase for gl utathionylspermidine disulphide was approx. 11 000-fold lower than tha t for glutathione disulphide. The much higher catalytic constant for t he mixed disulphide of glutathione and glutathionylspermidine (11% tha t of GSSG), suggests a possible explanation for the low turnover of tr ypanothione disulphide by E. coli glutathione reductase, given the app arent lack of a specific glutathionylspermidine disulphide reductase i n E. coli.