Studies on Rat Liver Glutamine Synthetase

Abstract
Rat liver glutamine synthetase is activated by Mg++ and by Mn++. Optimal activity of the Mg++ activated synthetase occurred at about pH 7.8. The pH optimum of the Mn++ activated enzyme varied from 6.2 at low Mn++concentrations to 4.4 at high Mn++concentrations. α‐N‐Ethyl‐L‐glutamine inhibits the synthetase activity. The inhibition is of a mixed type. The synthetase is also inhibited, to a lesser degree, by α‐N‐propyl‐L‐glutamine but not by α‐N‐butyl‐L‐glutamine.