Inhibition of glutathione peroxidase by coenzyme A

Glutathione peroxidase has been found to be extremely sensitive to inhibition by coenzyme A. Blocking the SH group of coenzyme A reduces the inhibitory effectiveness about 6-fold. It is thus possible that GSH peroxidase activity is regulated in vivo by the CoA/acyl CoA ratio. Dephospho-CoA was about 11-fold less effective than CoA, and pantetheine some 100-fold less effective. The kinetics of CoA inhibition were similar to those of 5′-ATP inhibition. It seems that CoA inhibits mainly because of its nucleotide properties.