Enzymatic destruction of histamine; study of the factors involved

Abstract

The influence of the enzyme concentration, as well as that of the kind -and concentration of the substract, upon the oxygen uptake when histaminase acts on histamine is studied. When the substract and its concentration remain constant the oxygen uptake rate is proportional to the enzyme concentration. For different samples of the same enzyme preparation the oxygen uptake depends of the kind and concentration of the substract employed. When different diamines are employed as substract, different results are attained, and even when the salt of the same amine changes (histamine dihydrochloride to fosfate) the total oxygen uptake changes. The influence of substract concentration works through an inhibition produced by substract «surplus », starting at concentrations of 0,6 mM HB/l. The oxygen uptake is produced apparently by two different ways; one is the disparison of histamine, and another one due to the oxidation of the metabolites previously formed. Accordingly with the facts previously reviewed the relationship between histamine destruction and oxygen uptake changes when the experimental conditions are different. When histamine dihydrochloride is used at concentrations between 0,5 and 1 mM HB/1. and the reaction spans through one hour, the value of the relationship is 0,083 ulO2/ug HB destroyed.