Peptic hydrolysis of gluten, glutenin and gliadin from wheat grain: Kinetics and characterisation of peptides

Abstract

The kinetics of the hydrolysis of gluten, glutenin and gliadin by pepsin was studied by following the reaction of the hydrolysate with ninhydrin and by SDS-gel electrophoresis. Glutenin was more rapidly hydrolysed than native molecules of gliadin and produced components of different size. The first stage of hydrolysis of gliadin resulted in the formation of fragments mainly in the range 25 000 and 10 000 daltons whereas polypeptides generated from glutenin had subunits of molecular weight (MW) in the range 65 000, 30 000 and 10 000. Further hydrolysis resulted in the formation of subunits of MW around 24 000 and 14 000 for glutenin and gliadin respectively. The final stage of hydrolysis produced a quantity of peptides of MW under 10 000 and a small quantity of free amino acids. No obvious differences in the molecular weights of the polypeptides released were found when the enzyme to gliadin ratio was varied. Components obtained from glutenin and gliadin were further characterised after gel filtration on Sephadex G50. Large polypeptides derived from both gliadin and glutenin contained large amounts of proline and glutamate. Surface hydrophobicity of derived components were different, and inferior to, those of the reduced glutenin and native gliadin. Reduction of disulphide bonds of digested polypeptides of glutenin showed the existence of peptides branched by interchain disulphide bonds. Peptic cleavage sites were probably located differently in glutenin and gliadin molecules.

Preparation and Functional Properties of Gluten Hydrolysates with Wheat‐Bug (Eurygaster spp.) Protease

“…The functional properties of protein hydrolysates are also influenced by specificity of proteolytic enzymes, the physical and chemical nature of the intact protein, and hydrolysis conditions (Mahmoud 1994). The enzymes used in protein modification include commercial enzymes such as Alcalase 2.4L, pancreatin trypsin 6.0S, pepsin, Protamex, and Neutrase fungal proteases; malt may also be used for hydrolysis of proteins (Masson et al 1986;Kong et al 2007).…”

Application of surface response methodology to optimize hydrolysis of wheat gluten and characterization of selected hydrolysate fractions

“…The solubility profile of the partially hydrolyzed protein improves along the whole pH scale, being generally higher with higher TCAI, since the protein does not form large aggregates even at the isoelectric pH. The solubility increase obtained from a limited proteolysis is attributed to the formation of either smaller and more hydrophilic polypeptide unities or soluble hydrophobic peptides,24 as well as the disruption of protein aggregates 25…”

Effect of accumulated resistance genes to Puccinia triticina on transfer of seed proteins

“…The gene products of specific Lr genes were at least twice heavier (Huang et al 2003) than enzymes controlling starch or its products degradation transferable trough the wheat cell wall. Furthermore, protein transfer from the seed started in units weighted 64 Kd (Masson et al 1986) similar as was of poly or disaccharides degrading enzymes. Also, when synthesis of the products and effect in germ or leaf cells was considered it was not sensed collision with PDI genes effect and purpose in maturating seed (Shewry & Halford 2002).…”