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γ‐Purothionins: amino acid sequence of two polypeptides of a new family of thionins from wheat endosperm
Author(s) -
Colilla Francisco J.,
Rocher Asuncion,
Mendez Enrique
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)81265-p
Subject(s) - endosperm , ammonium bicarbonate , glutenin , chemistry , biochemistry , fractionation , homology (biology) , cleavage (geology) , amino acid , protein primary structure , peptide sequence , chromatography , biology , organic chemistry , protein subunit , gene , paleontology , fracture (geology) , raw material
Two homologous sulfur‐rich basic polypeptides form wheat endosperm, so‐called γ 1 ‐purothionin and γ 2 ‐purothionin, are described. Purification involves extraction with volatile solvents and ammonium bicarbonate fractionation followed by reversed‐phase high‐performance liquid chromatography. The complete primary structure of these two polypeptides has been determined by automatic degradation of the intact, S‐carboxymethylated γ‐purothionins and peptides obtained by enzymatic cleavage. γ 1 ‐Purothionin and γ 2 ‐purothionin consist of 47 amino acids with an assessed molecular weight of 5239 and 5151 Da, respectively and 8 cysteines organized in 4 disulfide bridges. They present a high degree of homology among themselves (89% of identity) and are the first two thionin‐like polypeptides, so‐called y‐thionins, described from wheat endosperm.