INFLUENCE OF POLYPHENOLS ON POTATO PHOSPHORYLASE

The effects of a number of naturally occurring polyphenols on crude potato phosphorylase were reinvestigated in order to determine the mechanism of their action. While crystalline muscle phosphorylase is only weakly inhibited by 10-3 M chlorogenic acid, crude potato phosphorylase is 5 to 6 times more strongly inhibited. This difference in responses is due to the presence of o-diphenol oxidase in the potato preparation and most of the effective inhibitors are believed to be o-quinones. These probably attack sulfhydryl groups of the potato phosphorylase. The behavior of o-diphenols which contain primary amino groups in the side-chain is anomalous since they are either only weakly inhibitory or actually activate. © 1970.