Bovine Liver Glutamate Dehydrogenase: Tentative Amino Acid Sequence; Identification of a Reactive Lysine; Nitration of a Specific Tyrosine and Loss of Allosteric Inhibition by Guanosine Triphosphate

Abstract

Abstract. A tentative but almost complete amino acid sequence for the subunit peptide chain of bovine liver glutamate dehydrogenase indicates a minimal size of 506 residues with a molecular weight of 56,100, in accord with the physical size of the subunit of 55,900. Inactivation with pyridoxal 5'-phosphate, followed by reduction with sodium borohydride, has permitted identification of the essential lysine as residue 97. Nitration of tyrosine-412 is accompanied by loss of the allosteric inhibitory effect of guanosine triphosphate.Comparison of the sequences of glutamate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase has indicated that only two 12-residue sequences are similar in the two enzymes; this sequence includes reactive lvsine-97 of the former enzyme.Glutamate dehydrogenase (EC 1.4.1.3) occupies a central position in mammalian nitrogen metabolism since the reaction which it catalyzes provides the major pathway for the interconversion of a-amino group nitrogen and ammonia. Other important enzymes of amino acid metabolism usually employ pyridoxal 5'-phosphate in transamination or decarboxylation as the initial reaction step. The dehydrogenase is also of interest because its activity is subject to allosteric regulation by a variety of nucleoside polyphosphates, e.g., GTP is a strong inhibitory effector and ADP an activator.1 We have undertaken a study of the structure of glutamate dehydrogenase2 for a variety of reasons: first, because little is yet known regarding the structures and active sites of dehydrogenases; second, because this enzyme could serve as a useful model in attempts to understand the regulatory processes of multichain enzymes in general and of dehydrogenases in particular; third, because it would be useful to ascertain possible evolutionary relationships among the many dehydrogenases that utilize the pyridine nucleotide coenzymes, DPN and TPN. At present, only the sequence of glyceraldehyde-3-phosphate dehydrogenase (EC 1.2

Multiple Forms of Glutamate Dehydrogenase in Animals: Structural Determinants and Physiological Implications

“…Earlier studies on in vitro tyrosine nitration of bovine GDH with tetranitromethane showed that nitration of one tyrosine residue per subunit (Tyr412), which later was correctly identified as Tyr464 (Figure 2), does not affect the activity of the enzyme but decreases its response to inhibition by GTP [152,153,154]. In the resolved bovine GDH structure, Tyr464 is located in the middle of the antennae region, which suggests that the nitration of this residue may abrogate conformational changes of the antennae, thus perturbing the allosteric regulation of GDH [66].…”

Distance between the substrate and regulatory reduced coenzyme binding sites of bovine liver glutamate dehydrogenase by resonance energy transfer

“…The dialyzed enzyme was stored in aliquots at -75°C and was thawed immediately prior to use. A molecular mass of 56.1 kDa for the six identical peptide chains of the active form of glutamate dehydrogenase was used in the calculations [21].…”

Partial Similarities Between Yeast and Liver Alcohol Dehydrogenases

“…Similarities are indicated from comparisons without knowledge of enzyme structures (1)(2)(3) and from comparisons of short regions of glyceraldehyde phosphate dehydrogenase (GPDH), liver alcohol dehydrogenase (LADH), yeast alcohol dehydrogenase (YADH), lactate dehydrogenase (LDH), or glutamate dehydrogenase (GDH) (4)(5)(6)(7)(8)(9)(10). Long segments of possible but distant homology are found between GPDH and LADH (11) or GDH (12).…”