Isolation of a Cappelle-Desprez gliadin.

A Cappelle-Desprez gliadin, previously unreported, has been isolated. It appears to be a single-chain protein with a molecular weight of only 18 000, considerably lower than that of any other gliadin so far isolated. Its amino acid composition, though broadly typical of the class, has surprising characteristics, such as 7 Met, 7 CySSCy, but less Gln and Pro and no Lys or His. Although at acid pH the mobility is less than that of the γ-gliadin group, at pH 8.9 the molecule is still positively charged. The high isoelectric point implies that almost all the carboxyl side-chains are amidated. The gliadan contains no SH groups and does not appear to be a glycoprotein. The amino acid analysis suggests that microheterogeneity is present.