EFFECTS OF BROMOPYRUVATE ON CONTROL AND CATALYTIC PROPERTIES OF GLUTAMATE DEHYDROGENASE

When assayed with NAD, the time course of inactivation of glutamate dehydrogenase by bromopyruvate is biphasic. This analyses as two simultaneous first order reactions: the faster corresponds to destruction of an NAD activating site and the slower to the destruction of the active site. Both reactions are first order in bromopyruvate and both sites are protected by combinations of coenzymes and regulators. When assayed with NADP, activity loss is essentially a single first order process. When ADP is included in this assay, the activity loss profile is similar to that observed with NAD. With GTP included in this assay, the activity first increases, corresponding to a partial loss of GTP response, and then falls off in a first order reaction. The loss of response to both regulators is analysed in terms of a model in which approximately 50% of the regulatory sites are lost in a first order reaction. Evidence is presented that the sites binding ADP and GTP are not identical. Copyright © 1969, Wiley Blackwell. All rights reserved