The effect of organic solvents on mammalian histidine decarboxylase

Abstract

The action of rabbit-kidney histidine decarboxylase is considerably increased by the addition of very small quantities of several organic solvents. Benzene was one of the most active substances, increasing the yield of histamine from histidine 5- to 10-fold. A submaximal effect was produced by concentrations of benzene as low as 0.025 mg/ml. The effect is due to benzene in solution acting on the enzyme in solution. Evidence is presented that it does not depend on the presence of 2 liquid phases, nor on the suppression of bacteria, nor on a release of the enzyme from mitochondria or micro-somes. It is probably not due to the inhibition of histaminase. The ef-fect is probably due to a change in the enzyme, such as a break-up of micelles so that active groups previously buried become accessible.