Abstract: | Ferredoxin-dependent glutamate synthase has been isolated andpurified 170-fold from field bean (Vicia faba cv. Minor) leaves.The enzyme has a molecular weight of 145 000 and does not appearto contain non-haem iron. The Km values of the enzyme for glutamine,2-oxoglutarate, and ferredoxin are 330, 150, and 2 µMrespectively. The specificity of the enzyme is extremely highand no substitutes for glutamine have been found. Azaserineis a potent inhibitor of glutamate synthase. Chloroplasts from four species of plants have been shown tocarry out a light-dependent glutamate synthesis from glutamine.This reaction is also highly specific for glutamine and purifiedasparagine cannot substitute for glutamine. |