Inhibition of the catalytic subunit of phosphorylase phosphatase by oxalyl thioesters and its possible relevance to the mechanism of insulin action.

Oxalyl thioesters, especially S-oxalylglutathione, are shown to be effective inhibitors of the catalytic subunit of phosphorylase phosphatase. The amount of inhibition was found to be time dependent and partially reversed by thiols, thus suggesting that at least part of the inhibition is due to oxalylation of an enzymic thiol group. The possibility that the inhibition of the phosphatase by oxalyl thioesters may be important in vivo and that oxalyl thioesters may be functioning as negative intracellular messengers for insulin is discussed.