Abstract
NAD malic enzyme (EC. 1.1.1.39) has been purified from cauliflower (Brassica oleracea. var. botrytis) bud mitochondria. The enzyme exhibits complex regulatory properties being activated by a variety of metabolites including glycolytic intermediates, CoA, sulphate and Krebs cycle acids-the tricarboxylic acids with the exception of citrate being more effective than dicarboxylic acids. Fructose diphosphate which is a positive effector of the enzyme increases the affinity of the enzyme for L-malate.The enzyme is inhibited by glutamate, aspartate, phosphate and ATP, in the latter case the inhibition is largely due to chelation of Mg(2+). The plot of rate versus malate concentration is sigmoid at pH 7.0 with Mg(2+) but normal Michaelis-Menten kinetics are observed with Mn(2+). The molecular weight of the enzyme as measured by gel filtration is ca. 400000. The physiological significance of the responses to metabolites is discussed.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.