Pyridine nucleotides protein binding

This enzyme contains one mole of NAD per mole of protein. The pyridine nucleotide can be released by the action of p-chloromer-curibenzoate, and the enzyme activity is lost by this treatment. The reverse process occurs418 when the inactivated enzyme is incubated with cysteine and NAD , and this procedure has been used to bind radioactive NAD to the enzyme.330 A requirement for NAD has been demonstrated for various similar enzymes from other sources.65,420... 

The mechanism of hepatotoxicity is therefore currently unclear. It has been suggested that lipid peroxidation is responsible rather than covalent binding to protein. Arylation of other low molecular weight nucleophiles such as coenzyme A and pyridine nucleotides also occurs and may be involved in the toxicity. Bromobenzene is known to cause the inhibition or inactivation of enzymes containing SH groups. It also causes increased breakdown of phospholipids and inhibits enzymes involved in phospholipid synthesis. Arylation of sites on... 

TrxRs are homodimeric flavoproteins [80] that catalyze the NADPH-dependent reduction of thioredoxin (Trx), a ubiquitous 12 kDa protein that is the major protein disulfide reductase in cells [81], and belongs to the pyridine nucleotide-disulfide oxidoreductase family [82]. Each monomer includes an FAD prosthetic group, a NADPH binding site and an active site containing a redox-active selenol group. Electrons are transferred from NADPH via FAD to the active-site selenol of TrxR, which then reduces the substrate Trx [83]. The crystal structure of TrxR is shown in Fig. 13 [84],... 

Zinc Carbonic anhydrase, peptidases, phosphatases, pyridine nucleotide enzymes and other proteins Zn fimctioirs in substrate binding (e.g. for hydride transfer in ternary complexes with pyridine nucleotide enzymes), and in protein structure (e. g. alcohol dehydrogenase)... 

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