The amino-acid sequence of a purothionin from Triticum monococcum, a diploid wheat

Purothionins were extracted and purified from the diploid wheat Triticum monococcum. Two proteins were obtained, one of which was present in only very small amounts. The major purothionin of T. monococcum was sequenced and it had an amino acid sequence identical with that of the beta-purothionin of Triticum aestivum (hexaploid bread wheat). It is known that T. monococcum contains the wheat A genome, so the structural gene coding for the beta-purothionin must comprise a part of the A genome. There have been no observable (as amino acid replacements) changes in the DNA comprising either the beta-purothionin gene of T. aestivum or the purothionin gene of T. monococcum, since T. monococcum (or its wild equivalent, Triticum boeoticum) hybridized with the diploid wheat B genome progenitor and started the evolution from diploid to allohexaploid wheat. All of the investigated characteristics of the purothionin-like protein isolated in small amounts suggested that it was essentially identical in amino acid sequence with the T. monococcum purothionin. It may be a dimerized form of beta-purothionin.