Stereochemistry and function of oxaloacetate keto-enol tautomerase
Oxaloacetate keto-enol tautomerase, partially purified from porcine kidney, catalyzes the conversions of enol- to keto-oxaloacetate by a mechanism in which solvent protons end up equally distributed between the two prochiral positions at C3 of keto-oxaloacetate. This conclusion is based upon the observation that when enzyme catalyzed ketonization is conducted in /sup 3/H/sub 2/O in the presence of excess malate dehydrogenase and NADH, only 50% of the /sup 3/H in the isolated (2S)-(3-/sup 3/H)malate is labilized to solvent upon treatment with fumarase. Either the tautomerase operates on the basis of a highly unusual stereomechanistic principle or tautomerase activity is not an evolved property of the enzyme protein. As a result of an attempt to clarify the physiological importance of oxaloacetate tautomerase activity, keto-oxaloacetate was demonstrated to be directly transported across the inner membrane of rat liver mitochrondria, on the basis of the results of kinetic and isotope-trapping experiments.
- Research Organization:
- Univ. of Maryland Baltimore County, Catonsville
- OSTI ID:
- 5418088
- Report Number(s):
- CONF-8606151-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
- Country of Publication:
- United States
- Language:
- English
Similar Records
Superoxide anion radical (O sub 2 sup sm bullet minus ) mediated base-catalyzed autoxidation of. alpha. -keto enols
Mechanism of the keto-enol tautomerism in radical cations and gas-phase closed-shell systems
Related Subjects
ISOMERASES
BIOCHEMICAL REACTION KINETICS
STEREOCHEMISTRY
ENZYME ACTIVITY
NADH2
TRACER TECHNIQUES
TRITIUM COMPOUNDS
COENZYMES
ENZYMES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
NUCLEOTIDES
ORGANIC COMPOUNDS
REACTION KINETICS
550201* - Biochemistry- Tracer Techniques