Bironaĭte D A, Chenas N K, Lutsenko V V
Ukr Biokhim Zh (1978). 1993 Jan-Feb;65(1):97-100.
Quinones inactivate oxidized glutathione reductase (EC 1.6.4.2) from yeast with rate constants (ki) ranging from 0.03 M-1s-1 (p-benzoquinone) to 10(3) M-1s-1 (bromanyl). It is glutathione, but not NADP+ that protects the enzyme from inactivation, which shows that quinones interact with a glutathione-binding centre, cysteine-2, most probably. The mechanism of inactivation by quinones differs from that by nitrosoureas which inactivate only the reduced enzyme, modifying the reduced catalytic disulphide. 1,3-bis-(2-chloroethyl)-1-nitrosourea acts as the most rapid inactivator of the enzyme, possessing ki of 0.77 M-1s-1.
