The purification and properties of glutamine-dependent asparagine synthetase isolated from Lupinus albus

Abstract

Glutamine-dependent asparagine synthetase, which transfers the amide nitrogen of glutamine to aspartate has been purified from Lupinus albus . The enzyme has a very high affinity for glutamine although it is able to use ammonia as a substrate. The enzyme is inhibited by α-oxo acids, in particular α-oxoglutarate; the possible physiological role is discussed. The activities of various other enzymes involved in ammonia assimilation have been measured during development of the cotyledon. A pathway of the route of ammonia entry into various amino acids has been proposed. The substrate specificity of the enzyme has been investigated with analogues of glutamine, aspartate and asparagine.