ABSTRACT
The glutamine aminotransferases catalyze the transfer of the α-amino group of l-glutamine to a suitable α-keto acid acceptor, yielding α-ketoglutaramate and an l-amino acid. Although the reaction is reversible, l-glutamine utilization is favored because either α-ketoglutaramate spontaneously cyclizes or it is converted to α-ketoglutarate by ω-amidase. Glutamine aminotransferase and ω-amidase activities are widely distributed in rat organs. Meister and colleagues showed that ω-amidase activity is widespread in rat tissues, Novikoff hepatoma, yeast, Escherichia coli, Streptococcus faecalis, spinach leaves, and lettuce leaves. The enzyme was purified 40-fold from the rat liver and its catalytic activity was extensively studied. The catalytic properties of cytosolic rat liver ω-amidase may be summarized as follows: the enzyme catalyzes hydrolysis of 4- and 5-carbon dicarboxylic monoamides, and a variety of glutarate esters. It will also hydrolyze succinylhydroxamate but is inactive toward glutamine and asparagine.
