Conformation of NAD+ bound to allosteric L-lactate dehydrogenase activated by chemical modification.
On modification of arginine residues with 2,3-butanedione, the Thermus caldophilus L-lactate dehydrogenase is converted to an activated form that is independent of an allosteric effector, fructose 1,6-bisphosphate (Fru-1,6-P2). The conformation of NAD+ bound to the modified enzyme in the absence of Fru-1,6-P2 was investigated by means of proton NMR, analyzing the time dependence of the transferred nuclear Overhauser effect (TRNOE) and TRNOE action spectra. The inter-proton distances determined on TRNOE analysis indicated that both the nicotinamide riboside moiety and the adenosine moiety of NAD+ were in the anti conformation, the ribose rings being in the C3'-endo form. This conformation was almost the same as that of NAD+ bound to the native enzyme-Fru-1,6-P2 complex, rather than that of NAD+ bound to the free native enzyme. These results suggest that the C3'-endo-anti form of the enzyme-bound NAD+ is essential for the activation of the T. caldophilus L-lactate dehydrogenase.
Koide
S
S
Department of Agricultural Chemistry, Faculty of Agriculture, University of Tokyo, Japan.
Yokoyama
S
S
Matsuzawa
H
H
Miyazawa
T
T
Ohta
T
T
D000494:Allosteric Regulation; D000495:Allosteric Site; D001120:Arginine; D002074:Butanones / Q000494:pharmacology*; D003931:Diacetyl / Q000494:pharmacology*; D005635:Fructosediphosphates / Q000494:pharmacology*; D006598:Hexosediphosphates / Q000494:pharmacology*; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009243:NAD / Q000378:metabolism*; D013824:Thermus / Q000201:enzymology
D002074:Butanones; D005635:Fructosediphosphates; D006598:Hexosediphosphates; D009243:NAD; D001120:Arginine; D007770:L-Lactate Dehydrogenase; D003931:Diacetyl; C029063:fructose-1,6-diphosphate