Open AccessKinetic Studies with Rat‐Brain Succinic‐Semialdehyde Dehydrogenase
Author(s) -
RIVETT A. Jennifer,
TIPTON Keith F.
Publication year - 1981
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1981.tb06319.x
Subject(s) - nad+ kinase , uncompetitive inhibitor , chemistry , substrate (aquarium) , enzyme , stereochemistry , dehydrogenase , yield (engineering) , non competitive inhibition , biochemistry , thermodynamics , biology , physics , ecology
A simple procedure is described that gives an approximately 100‐fold purification of rat brain succinic‐semialdehyde dehydrogenase with a high yield. The enzyme exhibits a relatively low K m value for succinic semialdehyde (2. 5 μM) and is inhibited by high concentrations of that substrate in an uncompetitive manner with respect to NAD + ( K i = 150 μM), p ‐Hydroxybenzaldehyde was shown to give competitive inhibition with respect to succinic semialdehyde and uncompetitive inhibition with respect to NAD + . Initial rate studies in the presence of a fixed concentration of this inhibitor allowed a more accurate estimation of the kinetic parameters for the uninhibited reaction. The results of these studies, together with analysis of the dead‐end inhibition by AMP and the effects of NAD + and 3‐acetylpyridine‐adenine dinucleotide as alternative acceptors in the reaction, were consistent with the enzyme‐catalysed reaction obeying a compulsory‐order mechanism in which NAD + was the first substrate to bind to the enzyme and NADH was the last product to dissociate from it.