RESUMO
Dehydroalanine residues in peptides and proteins react with 4-pyridoethanethiol in alkaline solution to form 4-pyridoethyl cysteine residues, which after acid hydrolysis, give the corresponding amino acid. An experimental protocol has been developed, and with simple dehydroalanine derivatives, conversions of 96-99% are achieved. Tests with peptides and proteins show that serine and cysteine/cystine residues do not interfere with this analytical procedure. A sample of wool keratin contained 57 mumol dehydroalanine/g.
Assuntos
Alanina/análogos & derivados , Peptídeos/química , Proteínas/química , Compostos de Sulfidrila , Alanina/química , Concentração de Íons de Hidrogênio , Hidrólise , Piridinas/químicaRESUMO
Results of experiments on the procedure for amino acid analysis via analysis of the phenylthiocarbamyl amino acids are reported. It was found that yields of some amino acids varied in the presence of salt and with changes in the vacuum drying steps. An improved procedure is described which includes a standard addition of salt to the hydrolysate before drying it; the redrying step is omitted and the post derivatization drying is replaced by a simple addition of heptane to the reaction mixture.
