Incorporation of Histamine into Liver Protein in vivo

Abstract

RECENTLY we have described an enzyme system which catalyses the exchange of the amide group of protein-bound glutamine with primary amines, such as methylamine, putrescine, histamine, serotonin, etc., and also hydroxylamine and ammonia¹. The livers of rodents, and in particular of guinea pigs, are potent sources of the enzyme. This calcium-dependent enzyme not only catalyses the exchange with primary amines but also the hydrolysis of the amide group of protein-bound glutamine². In the absence of added amine the ɛ-amino group of protein-bound lysine may act as the replacing agent³. The enzyme was named ‘transglutaminase’. All mammalian organs examined, and in particular liver and brain, contain proteins which may act in vitro as amine-accepting substrates, as are also a number of purified proteins, such as casein, lactoglobulin, insulin, pepsin, etc.