A study of the acidic peptides formed on the partial acid hydrolysis of wool

A study of the peptides of cystine in partial hydrolysates of wool

“…Both amino and both carboxyl groups of cystine are probably involved in peptide linkages (Geiger, Harris, Mizell & Patterson, 1941;Lindley & Phillips, 1945), and Phillips (1946), on the basis of differences of reactivity of the combined cystine of wool towards sodium bisulphite and other mild reagents, has suggested that the more reactive fraction is associated with a polar environment. Consden, Gordon & Martin (1949) succeeded in identifying a number oflower peptides ofglutamic and aspartic acids in partial hydrolysates of wool, and we were encouraged to apply similar methods to identify the peptides of cystine. Although Consden et al (1949) found that some peptides of cystine with dicarboxylic amino-acids were present in a 3-day partial hydrolysate ofwool, much more ofthe cystine of such hydrolysates occurred in the neutral ionophoretic fraction.…”

“…Consden, Gordon & Martin (1949) succeeded in identifying a number oflower peptides ofglutamic and aspartic acids in partial hydrolysates of wool, and we were encouraged to apply similar methods to identify the peptides of cystine. Although Consden et al (1949) found that some peptides of cystine with dicarboxylic amino-acids were present in a 3-day partial hydrolysate ofwool, much more ofthe cystine of such hydrolysates occurred in the neutral ionophoretic fraction. The problem was, therefore, to separate the cystine peptides from this complex mixture, before attempting to employ paper chromatography.…”

“…The latter would of course include any peptide which contained an equal number of cysteic acid and basic residues. Oxidation has additional advantages: first, acidic substances are the easiest to investigate (Consden et al 1949); secondly, conversion to sulphonic acids avoids working with cystine compounds, which in general do not behave satisfactorily on paper chromatograms.…”

“…In other cases, where the synthetic peptide was not available, confirmation was obtained by comparison with closely related synthetic peptides. As in the investigation of peptides of dicarboxylic amino-acids (Consden et al 1949) the amounts of peptides present were assessed roughly by comparison of the intensities of the amino-acid spots produced after hydrolysis with the intensities produced by known amounts of amino-acids (cf. Polson, 1948).…”

“…EXPERIMENTAL General chromatographic methods. Separations on resin, ionophoresis, working up of ionophoretic fractions and analysis on paper chromatograms were carried out as described by Consden et al (1949). In all cases, twodimensional chromatography of the ionophoretic fractions was carried out with s-collidine as first solvent, and with phenol used in an atmosphere of coal gas and NH8 as second solvent.…”