Some Effects of Ethanol Extracts of Potatoes on the Activity of a Phosphorylase Preparation

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Abstract
In the presence of material extracted from potatoes by 80% ethanol, the amount of phosphate released from glucose-1-phosphate by potato phosphorylase, prepared by the original method of Hanes, is increased and the polysaccharide produced is a mixture of short chain maltodextrins and not amylose. The increase of phosphate results from the presence of priming material in the potato extract, which has been isolated in crude form, and is probably a mixture of [alpha] 1;4 linked maltodextrins. Prevention of amylose formation is due to a transferring enzyme contaminating the phosphorylase, which transfers maltosyl or larger units from the initial products of phosphorylase action to the glucose contained in the ethanol extract. When glucose labelled with C14 was added instead of the ethanol extract a series of maltodextrins was obtained, all of which were radioactive. No difference was found in the effects of extracts from potatoes stored at 25[degree]C or 0[degree]C, and the results do not support the views of Arreguin-Lozano and Bonner that potatoes contain a phosphorylase inhibitor, which disappears after low temperature storage.