THE WHEAT LEAF PHOSPHATASES: VII. FURTHER STUDIES ON INHIBITORS AT pH 5.7

Abstract

A survey of the inhibitory effect of various ribonucleosides, deoxyribonucleosides, sugars, phenols, and vitamins on the hydrolysis of 17 phosphatase substrates has been made. The more soluble ribonucleosides and deoxyribonucleosides inhibited the enzymatic hydrolysis of adenosine 5′-phosphate, phenolphthalein diphosphate, phenylphosphate, p-nitrophenyl phosphate, and in some cases the hydrolysis of adenosine 3′-phosphate, adenosine 2′-phosphate, and riboflavin 5′-phosphate. A 0.02 M concentration of orthophosphate inhibited the hydrolysis of all the compounds tested except adenosine 5′-phosphate and phenolphthalein diphosphate.These results, together with earlier findings, are discussed in terms of the concept that wheat leaf press juice contains two types of acid phosphatase, namely, β-glycerophosphatase and adenosine 5′-phosphatase. These two types of enzyme appear to have partially overlapping substrate specificities.