Enzymic properties of diamine oxidase from hog kidney

Abstract

DAO was partially purified from hog kidney by a procedure involving differential centrifugation, heat treatment and ammonium sulfate fractionation. The enzymic properties of partially purified DAO were studied with cadaverine and histamine as substrates and the following results were obtained. The specific activities of hog kidney DAO at the final step of purification were 183-fold and 125-fold those of the crude homogenate with histamine and cadaverine, respectively, as substrates. With cadaverine and histamine the pS maxima values were 3 × 10-3 M and 1 × 10-3 M and the pH optima were 7.1 and 6.5, respectively. All the diamines tested, (i.e. cadaverine, putrescine, hexamethylenediamine, histamine, ethylenediamine and agmatine) were oxidized with this enzyme, while monoamine, (i.e. tyramine, benzylamine, serotonin, ß-phenylethylamine, n-amylamine and n-propylamine) were not. DAO activity was inhibited by aminoguanidine, hydroxylamine, MPH and semicarbazide. The inhibitory effects were similar when either cadaverine or histamine was used as substrate. SH-reagents, such as PCMB and iodoacetoamide, did not affect DAO activity, but various metal ions, such as CuCl, Cu(N03)2, Zn(N03)2, A1C13 and Fe-(N03)3 were inhibitory. The inhibitory effect of AgN03 on DAO activity differed greatly, when using cadaverine and histamine as substrates. The temperature-inactivation curves of DAO measured with cadaverine and with histamine were different.