Complete amino acid sequence of puroindoline, a new basic and cystine‐rich protein with a unique tryptophan‐rich domain, isolated from wheat endosperm by Triton X‐114 phase partitioning

Abstract

A new basic protein has been isolated from wheat endosperm by Triton X‐114 phase partitioning. It contains five disulfide bridges and is composed of equal amounts of a polypeptide chain of 115 amino acid residues and of the same chain with a C‐terminus dipeptide extension. The most striking sequence feature is the presence of a unique tryptophan‐rich domain so that this protein isolated from wheat seeds has been named puroindoline. The similar phase partitioning behavior in Triton X‐114 of this basic eystine‐rich protein and of purothionins suggests that puroindoline may also be a membranotoxin that might play a role in the defense mechanism of plants against microbial pathogens.