ESR investigations of free and immobilized glutamate dehydrogenase

Abstract
The structure of bovine liver glutamate dehydrogenase was examined with 2,2,6,6‐tetramethyl‐4‐oxopiperidine‐1‐oxyl (TEMPO I) and 4‐((4‐(chloromercurio)benzoyl) amino)‐2, 2, 6, 6‐tetramethyl‐1‐piperidinyloxy (TEMPO II). ESR spectra from TEMPO I show that enzyme structure in the vicinity of this spin label was not distorted during immobilization to a Sepharose support. Deactivation studies with pyridoxal 5′‐phosphate indicate that immobilization did not expose additional binding sites to TEMPO I. Spectra from TEMPO II reveal that immobilization profoundly altered conformational change induced by α‐ketoglutarate and suppressed that induced by GTP and NADPH. This structural investigation provides insight into the altered kinetic properties of Sepharose‐immobilized glutamate dehydrogenase and suggests a fundamental difference between monomers and allosteric oligomers in their structural response to immobilization.

This publication has 21 references indexed in Scilit: