Subunits glutamate dehydrogenase

In primary structure, the NADP-dependent N. crassa enzyme shows clear but limited homology with the vertebrate glutamate dehydrogenases in the N-terminal two-thirds of the chain [98]. Interestingly, the NAD-dependent enzyme of N. crassa has a much larger subunit, with an apparently dissimilar sequence [99],... 

An enzyme from Bacillus sphaericus [100] catalyses this reaction. Like the well-known glutamate dehydrogenases it has a hexameric subunit arrangement, and is specific... 

Figure 9.10. The quaternary structure of glutamate dehydrogenase reveals a complex array of subunit interfaces. See color insert.

Fig. 2. Columns (a) to (d), electron micrographs of isolated molecules of glutamate dehydrogenase in various orientations. Column (e), computed projections of a model having spherical subunits. Column (f), two models of gluatamate dehydrogenase. Both models yield similar shadowgraph projections. The vertical axis is the 3-fold axis of each molecule, and the horizontal axis represents one of the three identical 2-fold axes. Courtesy of Josephs (139).

In many cases, 5 -FSBA reacts at active sites however, in bovine liver glutamate dehydrogenase, all the fluorosulfonylbenzoyl nucleosides react at regulatory sites. This enzyme is a hexamer of identical subunits, each of which has two regulatory sites for ADP, two for GTP, and two for NADH (one catalytic... 

Fig, 2, Effects of high-energy electron irradiation at -135°C on frozen solutions of fluorescein isothiocyanate-coupled glutamate dehydrogenase. Surviving enzyme activity (O) (RIS) and intensity of Coomassie blue stain of the monomer subunit on the gel electrophoregrams ( ) (target size) as a function of radiation exposure. (From Kempner and Miller, 1983.)... 

As described above, three enzymes are important for glutamic acid production ICDH, ODHC, and GDH. In particular, the activity of ODHC was thought to have an impact on glutamic acid production in C. glutamicum, as discussed in Section 11.4.2.1. ODHC consists of three subunits a catalytic subunit, Elo (OdhA) [52] a dihydrolipoamide acetyltransferase subunit, E2 (AceF) [53] and a dihydrolipoamide dehydrogenase subunit, E3 (Lpd) [54]. In addition, ODHC constitutes a supercomplex between the pyruvate dehydrogenase complex, which catalyzes the conversion from pyruvate to acetyl-CoA [53]. 

The most intensively studied strictly allosteric effect of GTP is its inhibition of the catabolic enzyme glutamate dehydrogenase from animals (76-81) and lower eukaryotes (82, 83). The animal enzyme is inhibited by micromolar concentrations of GTP and is stimulated by ADP (76-81). ATP also inhibits but only at much higher concentrations than required by GTP. GTP acts in part by regulating the level of polymerization of the enzyme subunits. 

P.J. Baker, K.L. Britton, PC. Engel, G.W. Farrants, K.S. Lilley, D.W. Rice, T.J. Stillman, Subunit assembly and active-site location in the structure of glutamate-dehydrogenase. Protein Struct. Fund Genet. 12 (1) (1992) 75-86. 

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