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Circular dichroism of complexes of NADH with self‐associating bovine liver glutamate dehydrogenase
Author(s) -
Zeiri Leila,
Reisler Emil
Publication year - 1979
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1979.360180916
Subject(s) - chemistry , cofactor , glutamate dehydrogenase , circular dichroism , polymerization , stereochemistry , gtp' , titration , enzyme , biochemistry , glutamate receptor , organic chemistry , polymer , receptor
The CD of GDH–NADH complexes was measured in order to reexamine the binding of coenzyme to GDH. The existence of two distinct Cotton effects associated with two separate NADH binding sites/subunit was confirmed with native, polymerizing and crosslinked, unpolymerizing enzyme. CD titration of the high‐affinity NADH sites revealed significant dependence of the optical activity of the bound coenzyme on the state of protein association. Molar ellipticity of bound NADH decreased with the increasing degree of polymerization of GDH. It is suggested that the high‐affinity NADH sites are loacted at or near the association interface. Binding of NADH to the low‐affinity sites, in the presence of GTP, leads to an inversion of the CD spectrum of GDH–NADH complexes. This inversion is not related to the polymerization of GDH. However, for proper analysis of the CD of NADH bound to the low‐affinity sites, a correction for the effect of polymerization on the optical activity of NADH bound to the high‐affinity sites is required.