Carbonyl oxygen exchange evidence of imine formation in the glutamate dehydrogenase reaction and identification of the "occult role" of NADPH.

Fisher, Harvey F.; Viswanathan, T. S.

doi:10.1073/pnas.81.9.2747

Cited by 12 publications

(4 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…although the deviations indicate some additional complexity in both the initial and the very late stages of the reaction. 4 Indirect evidence from O 18 exchange studies implicated the involvement of an enzyme R-iminoglutarate-NADPH complex (ERI) as an obligatory intermediate in this reaction (11), and chemical necessity appeared to dictate the requirement of the formation of an R-carbinolamine complex (ERC) as an ensuing step. However, the findings presented here offer the first direct physical evidence of the actual occurrence of these two postulated entities.…”

Section: Substituting the Values Of [Eri] [Erc] And [Erk]mentioning

confidence: 99%

Identification and Characterization of Kinetically Competent Carbinolamine and α-Iminoglutarate Complexes in the Glutamate Dehydrogenase-Catalyzed Oxidation of l-Glutamate Using a Multiwavelength Transient State Approach

1998

View full text Add to dashboard Cite

A highly constrained and heavily overdetermined multiwavelength transient state kinetic approach has been used to study the oxidative deamination of L-glutamate catalyzed by beef liver glutamate dehydrogenase. Spectra generated using the known enzyme-reduced coenzyme-substrate spectrum served as models for deconvolution of kinetic scan data. Deconvolution of the multiwavelength time course array shows formation of three distinguishable intermediates in the reaction sequence, an ultrablue-shifted complex, an ultrared-shifted complex, and a blue-shifted complex. The ultrablue-shifted entity is identified as the enzyme-NADPH-alpha-iminoglutarate complex (ERI) and the ultrared as the enzyme-NADPH-alpha-carbinolamine complex (ERC). The blue-shifted complex is characterized as the E-NADPH-ketoglutarate species (ERK). The location of these species along the reaction coordinate has been determined and their kinetic competency in the reaction sequence has been established by fitting the concentration time courses of the components for both the alpha-deuterio- and the alpha-protio-L-glutamate reactions to the now highly constrained differential equations derived from a kinetic scheme involving the sequential formation of alpha-iminoglutarate, alpha-carbinolamine, and alpha-ketoglutarate-reduced coenzyme complexes, following the formation of two prehydride transfer complexes.

show abstract

Section: Substituting the Values Of [Eri] [Erc] And [Erk]mentioning

confidence: 99%

Identification and Characterization of Kinetically Competent Carbinolamine and α-Iminoglutarate Complexes in the Glutamate Dehydrogenase-Catalyzed Oxidation of l-Glutamate Using a Multiwavelength Transient State Approach

1998

View full text Add to dashboard Cite

show abstract

“…They are grouped into NAD‐specific (EC 1.4.1.2), NADP‐specific (EC 1.4.1.4) and dual [NAD(P)]‐specific (EC 1.4.1.3) forms based on which pyridine nucleotide can serve as the substrate. Regardless of their coenzyme specificity, all GDHs share a common chemical mechanism that invokes a bound ‘iminoglutarate’ intermediate [3–6].…”

Section: Introductionmentioning

confidence: 99%

Competitive inhibition of glutamate dehydrogenase reaction

Choudhury

Punekar

2007

FEBS Letters

View full text Add to dashboard Cite

Irrespective of their pyridine nucleotide specificity, all glutamate dehydrogenases share a common chemical mechanism that involves an enzyme bound 'iminoglutarate' intermediate. Three compounds, structurally related to this intermediate, were tested for the inhibition of purified NADP-glutamate dehydrogenases from two Aspergilli, as also the bovine liver NAD(P)-glutamate dehydrogenase. 2-Methyleneglutarate, closely resembling iminoglutarate, was a potent competitive inhibitor of the glutamate dehydrogenase reaction. This is the first report of a non-aromatic structure with a better glutamate dehydrogenase inhibitory potency than aryl carboxylic acids such as isophthalate. A suitably located 2-methylene group to mimic the iminium ion could be exploited to design inhibitors of other amino acid dehydrogenases.

show abstract

“…Previous studies have suggested that the glutamate‐forming reaction proceeds as follows. 2‐OG is firstly converted to 2‐iminoglutarate (2‐IG) through a nucleophilic attack by ammonia, and is then reduced by NADPH to yield glutamate . Therefore, 2‐IG has been proposed as a reaction intermediate; however, the synthesis of this compound by GDH has not yet been directly elucidated due to the low stability of the putative intermediate in aqueous solution.…”

mentioning

confidence: 99%

Crystal structure of the 2‐iminoglutarate‐bound complex of glutamate dehydrogenase from Corynebacterium glutamicum

et al. 2017

View full text Add to dashboard Cite

show abstract

Carbonyl oxygen exchange evidence of imine formation in the glutamate dehydrogenase reaction and identification of the "occult role" of NADPH.

Abstract: Although (1), it has generally been assumed that the mechanism of this reaction involves the initial formation of enzyme-bound a-iminoglutarate from a-ketoglutarate and ammonia (N) followed by the reduction of that imine by NADPH in a subsequent step: o NH3 NH

Cited by 12 publications

References 12 publications

Identification and Characterization of Kinetically Competent Carbinolamine and α-Iminoglutarate Complexes in the Glutamate Dehydrogenase-Catalyzed Oxidation of l-Glutamate Using a Multiwavelength Transient State Approach

Identification and Characterization of Kinetically Competent Carbinolamine and α-Iminoglutarate Complexes in the Glutamate Dehydrogenase-Catalyzed Oxidation of l-Glutamate Using a Multiwavelength Transient State Approach

Competitive inhibition of glutamate dehydrogenase reaction

Crystal structure of the 2‐iminoglutarate‐bound complex of glutamate dehydrogenase from Corynebacterium glutamicum

Contact Info

Product

Resources

About