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...

Human P-glycoprotein (P-gp) is a cell surface drug efflux pump that contains two nucleotide binding domains (NBDs). Mutations were made in each of the Walker B consensus motifs of the NBDs at positions D555N and D1200N, thought to be involved in Mg(2+) binding. Although the mutant and wild-type P-gps were expressed equivalently at the cell surface and bound the drug analogue [(125)I]iodoarylazi...

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...

The first iodinated cyclopentadienone was isolated and its structure was confirmed by single crystal X-ray analysis. Based on this intermediate, the first direct C-C bond formation on cyclopentadienone ring was achieved. The photo induced intramolecular charge transfer of alkynylated cyclopentadienones was evaluated by solvent polarity effect on their electronic absorption spectra.