Tyrosine residues dehydrogenases

Phosphorescence and ODMR are additional spectroscopies that can be used to investigate intramolecular interactions that affect tyrosine residues in proteins and polypeptides/215,216) An example is tyrosine and tyrosinate in horse liver alcohol dehydrogenase.(202) The same approach has been used to study the role of tyrosine in the mechanism of action of carboxypeptidase B.(21/,218) jn botli these proteins, as in other proteins which contain both... 

Turnover number, succinate dehydrogenase, 236-237 Tyrosine residues cytochrome hi reductase, 163 cytochrome c peroxidase, 355 glyceraldehyde-3-phosphate dehydrogenase, 21... 

Nishino, T., and Nishino, T., 1987, Evidence for a tyrosine residue in the nicotinamide adenine dinucleotide binding site of chicken liver xanthine dehydrogenase. Biochemistry 26 3068n3072. 

Catalase is also able to oxidize a few small molecules, in particular ethanol (the pro-R-hydrogen atom is stereospecifically removed as in the alcohol dehydrogenase-mediated oxidation). Several heme-catalase three-dimensional structures are available from the fungus Penicillium Vitalefrom beef liver, or from the bacterium Microccocus lysodeikticus The proximal ligand site of these heme-catalases is occupied by a tyrosine residue (Tyr-357 and Tyr-339 in beef liver and bacterial catalases, respectively) with an Fe—O distance of 1.9 A (see Figure 3). 

There are several points of attack on the protein molecule, and in glutamate dehydrogenase and RNase, exposure to UV in the presence of psoralen extensively modified histidine, methionine, tryptophan, phenylalanine and tyrosine residues by photo-oxidation. ... 

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.)...

Structure of a helix F interface of human 11 (3-hydroxysteroid dehydrogenase types 1 and 2. The a helix F part of the dimer interface on 1 ip-HSD-1 and -2 is shown along with side chains of the highly conserved tyrosine and lysine residues and other residues that are oriented into the cavity that binds substrate and nucleotide cofactor. 

Figure 6a shows the modeled oc helix F interface in human 17 3-hydroxysteroid dehydrogenase type 1 in which phenylalanine-160 and alanine-161 form an anchor. Both residues have important stabilizing interactions across the dimer interface. Alanine-161 is 4.1 A from alanine-161 on the other subunit. Alanine-161 has a hydrophobic interaction with alanine-157, which is in the segment between the conserved tyrosine-155 and lysine-159. There is a hydrophobic... 

Dehydrogenases exhibit a fluorescence similar to that of tryptophan. Irradiation of dehydrogenases at 280 nm gives an emission maximum at 340 nm (Figs. 2 and 3). This pattern is characteristic of enzymes which contain tryptophan and can be designated protein fluorescence. The other side residues, tyrosine or phenylalanine, fluoresce very weakly and probably do not contribute significantly to the fluorescence of the enzyme7). 

The short-chain dehydrogenases, originally so called because the linear sequences then available rarely exceeded 250 residues, use tyrosine as the acid-base. As longer sequences with the same fold have become available, the name is something of a misnomer and the M,. range is now 250-350 residues for the core structure.They have B-side (proS) stereospecilicity for the coenzyme, which they bind in the syn conformation. Structurally, they adopt the same protein fold, much like a GH family, even though the degree of... 

Covalent quinoproteins possess protein-derived cofactors derived from aromatic amino acid residues. These enzymes contain a posttranslationally modified tyrosine or tryptophan residue into which one or two oxygens has been incorporated (Figure 3). In some cases, the quinolated amino acid residue is also covalently cross-linked to another amino acid residue on the polypeptide. Tyrosine-derived quinone cofactors occur in oxidases from bacterial, mammalian, and plant sources. Tryptophan-derived quinone cofactors have been found thus far in bacterial dehydrogenases. 

Table VIII lists the side chain hydrogen bonds within one subunit. Table IX gives the distances of all tyrosines and tryptophans within the molecule to the center of the nicotinamide in the red subunit and these are depicted in Fig. 14. Table IX also describes the environment of these residues. Amino acid residues that have been chemically modified will be further discussed in Section II,B. Tryptophan has not been modified in LDH, but Shallenberg had implicated it in the catalytic mechanism of many dehydrogenases (152). His data could not be confirmed (153,154). As can be inferred from Table IX, there is no tryptophan in the neighborhood of the active site.

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