Glutamate dehydrogenase cysteine residues

Fia. 4. Amino acid sequences of bovine (B), chicken (C), and rat (R) liver glutamate dehydrogenases. The chicken enzyme possesses three additional residues at the NHa-terminal end with the NHa-terminal residue indicated as cysteine although it was found as cysteic acid. The unpublished data (260) for the rat enzyme were... 

The two estrogen der y ives, 4-mercuriestradiol (4ME) and 2-diazoestrone sulfate (DZE) react rapidly with cysteine residues in glutamate dehydrogenase DZE also reacts with pyruvate kinase. Estradiol slows the rate of reaction of these derivatives, which is consistent with an affinity labeling mechanism. The reactivity and instability of these derivatives, however, limit their utility. 

Figure 1.9 Examples of functionally important intrinsic metal atoms in proteins, (a) The di-iron center of the enzyme ribonucleotide reductase. Two iron atoms form a redox center that produces a free radical in a nearby tyrosine side chain. The iron atoms are bridged by a glutamic acid residue and a negatively charged oxygen atom called a p-oxo bridge. The coordination of the iron atoms is completed by histidine, aspartic acid, and glutamic acid side chains as well as water molecules, (b) The catalytically active zinc atom in the enzyme alcohol dehydrogenase. The zinc atom is coordinated to the protein by one histidine and two cysteine side chains. During catalysis zinc binds an alcohol molecule in a suitable position for hydride transfer to the coenzyme moiety, a nicotinamide, [(a) Adapted from P. Nordlund et al., Nature 345 593-598, 1990.)...

Johnson, A.R., and Dekker, E.E. (1996) Woodward s reagent K inactivation of Escherichia coli L-threo-nine dehydrogenase Increased absorbance at 340-350 nm is due to modification of cysteine and histidine residues, not aspartate or glutamate carboxyl groups. Protein Sci. 5, 382-390. 

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