The action of pepsin on the reserve proteins of some leguminous seeds.
The action of pepsin on the 11-S and 7-S proteins of vetch, 11-S protein of soybean and 7-S protein of Phaseolus vulgaris was investigated. The first three proteins are hydrolyzed almost completely, the rate of hydrolysis being close to that of hemoglobin, while the hydrolysis of Ph. vulgaris 7-S protein stops after the cleavage of only 2,4% of peptide bonds. The nonhydrolyzable high molecular weight core makes up to 87% of the initial protein and differs from the latter in its electrophoretic mobility and sedimentation coefficient. The action of pepsin does not increase the digestibility of Ph. vulgaris 7-S protein by trypsin. After the consecutive action of these enzymes about two thirds of the protein remain unhydrolyzed. The digestion of Ph. vulgaris 7-S protein by pepsin is completed only after its denaturation by heat treatment or by the action of 6 M guanidine hydrochloride.
D007700:Kinetics; D010434:Pepsin A / Q000378:metabolism; D010940:Plant Proteins; D011489:Protein Denaturation; D012639:Seeds; D013025:Glycine max
D010940:Plant Proteins; D010434:Pepsin A