Lactate dehydrogenase displays absolute stereospecificity in the transfer of the prochiral hydrogen of NADH.
The frequency of nonstereospecific hydride transfers to and from the C-4 of NAD+ by porcine heart lactate dehydrogenase has been determined to be less than 1 out of every 10(7) hydride transfers, using a method employing a dynamic equilibrium which allows for the detection of extremely rare (less than 1 in 10(8] nonstereospecific transfers. A detailed protocol is presented. The inability to detect unequivocally a nonstereospecific transfer either to or from the si face of the nicotinamide ring (pro-4S hydrogen to NADH) indicates that the transition state for the more favorable transfer of the pro-4R hydrogen is at least 10 kcal/mol lower in energy.
LaReau
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RD
Department of Chemistry, Brown University, Providence, Rhode Island 02912.
Anderson
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VE
D000818:Animals; D003903:Deuterium; D006859:Hydrogen; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D009206:Myocardium / Q000201:enzymology; D009243:NAD / Q000378:metabolism*; D010084:Oxidation-Reduction; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid; D011865:Radioisotope Dilution Technique; D013237:Stereoisomerism; D013552:Swine; D014316:Tritium
D007773:Lactates; D011773:Pyruvates; D009243:NAD; D014316:Tritium; D019344:Lactic Acid; D006859:Hydrogen; D019289:Pyruvic Acid; D003903:Deuterium; D007770:L-Lactate Dehydrogenase