Reaction of azide radicals with amino acids and proteins.
The azide radical N3 reacts selectively with amino acids, in neutral solution preferentially with tryptophan (k (N3 + TrpH) = 4.1 X 10(9) dm3 mol(-1s-1) and in alkaline solution also with cysteine and tyrosine (k(N3 + CyS-) = 2.7 X 10(9) dm3 mol-1s-1) and k(N3 + TyrO-) equals 03.6 X 10(9) dm3 mol-1s-1). Oxidation of the enzyme yADH by N3 involves primary attacks, mainly at tryptophan residues, and subsequent slow secondary reactions. N3-induced inactivation of yADH is likely to occur upon oxidation of tryptophan residues in the substrate binding pocket (58-TrpH and 93-TrpH) since the substrate ethanol although unreactive with N3, protects yADH and since elADH, which does not contain tryptophan in the substrate pocket, is comparatively resistant against N3-attack. N3 exhibits low reactivity with nucleic acid derivatives and it is inert towards aliphatic compounds such as methanol and sodium dodecylsulphate.
D000429:Alcohol Oxidoreductases / Q000528:radiation effects; D000596:Amino Acids; D001386:Azides; D004789:Enzyme Activation / Q000528:radiation effects; D005609:Free Radicals; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011506:Proteins; D011675:Pulse Radiolysis
D000596:Amino Acids; D001386:Azides; D005609:Free Radicals; D011506:Proteins; D000429:Alcohol Oxidoreductases