Mechanisms that have been proposed for peroxidase-catalyzed iodination require the utilization of 1 mol of H2O2 for organic binding of 1 mol of iodide. When we measured the stoichiometry of this reaction using thyroid peroxidase or lactoperoxidase at pH 7.0, we consistently obtained a ratio less than 1.0. This was shown to be attributable to catalase-like activity of these enzymes, resulting in...

The active site of antibody directed against the negatively charged p-azobenzenearsonic acid group has been shown to contain an iodine-reactive residue. The first evidence was provided by Pressman and Sternberger (1)) who demonstrated that iodination destroys the precipitating capacity of this antibody and that the loss can be prevented by the prior addition of the homologous hapten. Subsequent...

Phosphorylation of tyrosine residues by protein tyrosine kinases (PTK) and phosphotyrosine/Src homology 2 (SH2) domain interactions are crucial not only for signal transduction but also for regulation of PTK activity. Tyrosine residues also receive nitration and halogenation under oxidative conditions. It has been reported that nitration of tyrosine residue caused peptides to be a poor substrat...

Iodination of bovine pancreatic ribonuclease A at O” and pH 8.5 leads to the formation of 3 iodinated tyrosyl residues and 1 iodinated histidyl residue. The yield of iodinated amino acids is not significantly different at 24’. Carboxymethylation of histidine-119 reduces the total organic iodine from -8 to -6 g atoms per mole. This decrease is almost entirely accounted for by a lack of iodohisti...

Regioselective palladium catalysed coupling reactions are achieved in good to high yields, starting from either 3,5-dichloro- or 3,5-dibromoisothiazole-4-carbonitriles 1 and 2, providing 3-halo-5-(hetero/aryl, alkenyl and alkynyl)isothiazoles 3, 4, 6-9 from Stille couplings, 3-halo-5-(hetero/arylethynyl)isothiazoles 14-19 from Sonogashira and 5,5'-bi(3-chloroisothiazole-4-carbonitrile) (13) fro...