Aspartic proteinase from wheat seeds: isolation, properties and action on gliadin

Abstract

Wheat endosperm was shown to contain an aspartic proteinase capable of hydrolyzing the wheat storage protein, gliadin, in vitro. The enzyme was purified to homogeneity by affinity chromatography on bacilliquin-silochrome, diethylaminoethyl-Toyopearl ion-exchange chromatography, chromatofocusing, and preparative polyacrylamide gel electrophoresis. The sedimentation constant of the enzyme was 3.4 S and the relative molecular mass (Mr), determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was 58000 dalton (Da). The purified enzyme was completely inhibited by pepstain whereas other enzyme inhibitors did not affect its activity. The enzyme was found to hydrolyze mainly ω- and γ-gliadins with Mr's of 67000-95000 Da, with maximal activity at pH 4.5. The data make it possible to suggest that the enzyme has an endogenous function by initiating proteolysis of storage proteins in germinating wheat seeds.

Aspartic proteases gene family in rice: Gene structure and expression, predicted protein features and phylogenetic relation

“…Aspartic proteases have been purified from seeds in many plants, including wheat (Belozersky et al, 1989), Arabidopsis thaliana (Mutlu and Gal, 1999), sorghum (Macedo et al, 1999), buckwheat (Timotijevic et al, 2006), barley (Zhang and Jones, 1999), sunflower (Park et al, 2000) and Theobroma cacao (Guilloteau et al, 2005), which were speculated as conditioning protein degradation. Germination of seeds requires the action of a number of proteolytic enzymes that hydrolyze the seed-storage proteins to provide amino acids to growing plant (Higgins, 1984).…”

Molecular and biochemical characterisation of two aspartic proteinases TcAP1 and TcAP2 from Theobroma cacao seeds

“…Often, these proteins have been shown to cleave peptide bonds between amino acid residues with large hydrophobic side chains (Kervinen et al 1993;Ramalho-Santos et al 1996). Plant aspartic proteinases have been proposed to be involved in storage-protein processing during seed development , and in protein degradation during seed germination (Belozersky et al 1989). Others have been proposed to be involved in senescence, for example in orange tree leaves (Garcia-Martinez and Moreno 1986), in barley leaves (Kervinen et al 1990), and in the flowers of cardoon (Heimgartner et al 1990).…”

Primary structure of a barley‐grain aspartic proteinase

“…Their sizes range from 28 kDa in cucumber to 65 kDa in rice. Some physiological functions, like the digestion of storage proteins at the onset of germination in rice [15], barley [20, 211 and wheat [17,22] as well as the digestion of pathogenesisrelated proteins in tomato leaves [I 31, have been suggested. However, the exact physiological function of plant aspartic proteinases remains to be elucidated.…”