A modified assay system for enzymes involved in N-acetyl group transfer reactions: its use to study enzymes involved in ornithine biosynthesis in plants.

A new method for assaying the enzymes N2-acetyl-L-ornithine:L-glutamate N-acetyltransferase (EC 2.3.1.35) and acetyl-coenzyme A:L-glutamate N-acetyltransferase (EC 2.3.1.1) has been designed. This assay system is based on the separation of N-[14C]acetylglutamate from N-[14C]acetylornithine or [14C]acetyl-coenzyme A by differential absorption of these compounds to DEAE anion-exchange disks. The procedure is simple and sensitive and eliminates the use of ion-exchange resin columns. Using the present method, the inhibition of the enzyme N2-acetyl-L-ornithine:L-glutamate N-acetyltransferase by alpha-methylornithine and N-bromoacetylornithine was studied.