A Bacterial Enzyme Which Converts Creatine into its Anhydride Creatinine. ∗

Abstract

We have previously described the preparation from two bacterial species (NC and HR) of enzymic systems that are highly specific for the decomposition of creatine and creatinine. 1 , 2 These enzymic systems function only under aërobic conditions and convert creatine and creatinine into urea, ammonia, and other compounds. We have now observed that the washed cells of the NC bacterial species are capable of converting creatine into creatinine under anaërobic conditions; the creatinine so produced can then be decomposed by the same bacterial suspension when the conditions are rendered aërobic.

The new enzyme has been obtained in aqueous solution, free of the cellular structure, by killing the cells with cold acetone, or with toluol and chloroform.

This enzyme appears to exhibit a high degree of specificity for creatine, since it does not convert the closely related compound glycocyamine into glycocyamidine, nor does it change hydantoic acid into its anhydride, hydantoin. The enzyme does not produce creatine or creatinine from arginine, a possible precursor of creatine in the animal body. Methyl guanidine and acetic acid, component parts of creatine, are not synthesized into the latter compound by the enzyme.

The enzyme is not produced when the bacterial cells are grown in a medium which does not contain creatine; it seems, therefore, to belong to the group of “adaptive enzymes” which are produced only in the presence of their specific substrate. The conversion of creatine into creatinine offers an opportunity for the study in vitro of (a) the enzymatic production of a biologically important cyclic compound from an aliphatic one, and (b) the enzymatic combination of an amino and a carboxyl group to form the important CO-NH linkage