γ‐Purothionins: amino acid sequence of two polypeptides of a new family of thionins from wheat endosperm

Abstract

Two homologous sulfur-rich basic polypeptides form wheat endosperm, so-called y,-purothionin and y,-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 y-purothionins and peptides obtained by enzymatic cleavage. y,-Purothionin and y,-purothionin consist of 47 amino acids with an assessed molecular weight of 5239 and 5151 Da, respectively and 8 cysteines organ&J 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 endospemt.Wheat thionin; Amino acid sequence; y-Purothionin

Isolation and characterisation of plant defensins from seeds of Asteraceae, Fabaceae, Hippocastanaceae and Saxifragaceae

“…The length of the fully sequenced peptides varies from 49 amino acids for Ct-AMP1 to 54 amino acids for Hs-AFP1. All the peptides show a high degree of homology to each other as well as to the plant defensin Rs-AFP2 from radish seeds [5], the N-terminal 20 amino acids of PTh-Stl from potato tubers [7], the c~-amylase inhibitor from Sorghum seeds, SI~2 [10] and the y-thionins from wheat and barley seeds [8,9] (Fig. 2).…”

“…At least four different classes of cysteine-rich antimicrobial peptide have been isolated from seeds of barley and wheat [2], Mirabilis jalapa [3], Amaranthus caudatus [4] and five Brassicaceae species [5,6]. This latter class of peptide appears to be widely distributed in the plant kingdom and homologous peptides have been isolated from seeds [7][8][9][10] or identified via sequencing of eDNA clones [11][12][13][14] in both monocot and dicot species. A number of different in vitro activities have been attributed to this class of peptide including inhibition of in vitro protein synthesis [8,9], inhibition of ~-amylases [10] and antimicrobial activity [5][6][7].…”

“…This latter class of peptide appears to be widely distributed in the plant kingdom and homologous peptides have been isolated from seeds [7][8][9][10] or identified via sequencing of eDNA clones [11][12][13][14] in both monocot and dicot species. A number of different in vitro activities have been attributed to this class of peptide including inhibition of in vitro protein synthesis [8,9], inhibition of ~-amylases [10] and antimicrobial activity [5][6][7]. Based on the inhibitory activity of at least some members of this peptide family to plant pathogenic fungi, their expression patterns in planta [11,12] and their three-dimensional structures, which show homology to that of insect defensins [15], we have proposed the name plant defensin to describe this family [16].…”

Defensins: A Novel Approach to Use Plant Antimicrobial Peptides as an Alternative to Antibiotics

“…Mendez and co-workers [9,10] and these peptides named y-thionins have size (5 kD) and same number of disulfide bridges(four)as a -and p-thionins. [11][12][13] Proteins isolated from seeds of monocot and dicot are found be homologous to "y" thionins [14][15][16][17] or identified via the sequencing of cDNA clones.…”

Expression of the ZmDEF1 gene and α-amylase inhibitory activityof recombinant defensin against maize weevils

“…Plant defensins attract great interest as they are reported to be involved in different defense pathways in plants (Selitrennikoff, 2001). Plant defensins are multifunctional, and, according to many studies, they show antifungal and antibacterial activity (Wang et al, 2011), inhibition of trypsin and α-amylase activities (Melo et al, 2002), inhibition of protein synthesis (Colilla et al, 1990), increased tolerance to heavy metals (Mirouze et al, 2006), and regulation of plant growth and development (Stotz et al, 2009). Based on their sequential characteristics and functions (van der Weerden and Anderson, 2013), plant defensins are divided into 18 groups.…”