Abstract
Abstract
Benzylamine oxidase (BzAO) is an amine oxidase with a widespread distribution in mammalian tissues. The present study has characterized certain properties of BzAO using homogenate of rat skull as the enzyme source. BzAO activity was assayed after inactivation of monoamine oxidases with pargyline and was shown to be distinct from diamine oxidase, polyamine oxidase, lysyl oxidase, and ceruloplasmin. Only aromatic amines with a primary amino group were found to interact with BzAO. 2-Phenylethylamine, tryptamine, p-tyramine, and dopamine acted as substrates but were deaminated less rapidly than benzylamine, which showed an apparent K m value of 2.8 μM and a V max value of 220 pmole deaminated mg · protein-1 · min-1. (+)-α-Methylphenylethylamine (amphetamine) acted as a noncompetitive inhibitor of benzylamine deamination. Overall, the K m and K i values of the amines for BzAO increased with increasing polarity. It is concluded that the nonprotonated form of benzylamine acts as substrate for the enzyme and that the catalytic mechanism of skull BzAO appears consistent with a double displacement or “ping-pong” reaction. Compared with brain monoamine oxidase type B, benzylamine is 50 times more avid for BzAO, which, in turn, appears to exhibit a lower K m for oxygen than monoamine oxidase type B.
Get full access to this article
View all access options for this article.