Effect of Amylase on Formation of Hexose-phosphate by Muscle Extract.

Abstract

The mechanism by which the pancreatic factor 1 inhibits the formation of hexose-phosphate 2 and therefore glycolysis in muscle extract has been shown by Case and McCullagh 3 to be a direct action on the starch or glycogen used as the source of carbohydrate. Hydrolysis of these carbohydrates before the esterification of their mono-saccharid derivatives with phosphate seems a necessary assumption. Complete inhibition is difficult to explain since always there remains a residue of carbohydrate with but slight reducing value. We are, however, able to confirm these observations and find also that muscle amylase added in sufficient quantities produces marked inhibition of glycolysis.

We report here a study of the action of pancreatic diastase on the formation of hexose-phosphate by muscle extract, undertaken with a view to establishing a possible rôle of amylase in muscle extract glycolysis. If hydrolysis of starch or glycogen is a necessary step before its esterification with phosphate, it should be possible to increase the rate of esterification by accelerating the hydrolysis of the carbohydrate, unless muscle extract contains an optimum amount of amylase for this purpose. Muscle extract prepared by extraction with salt solution for one-half hour has an almost optimum amylolytic activity and the addition of small quantities of amylase has no effect or slightly inhibits the formation of hexose phosphate. However, muscle extracts prepared by brief extraction with water have a lower amylolytic activity and on these extracts the acceleration in the rate of formation of hexose-phosphate by added amylase is shown in the following chart. To the water extract of muscle Na₂HPO₄ was added to give a concentration of 200 mg. P. per 100 cc. The concentration of NaHCO₂ was .025 M. and NaF .02 M.