Isolation and Composition of the Seed Globulins of Winged Bean, Psophocarpus tetragonolobus (L.) DC

Abstract

The amino acid composition of winged bean seed meal is similar to that of soybean but their storage globulins are quite different. Winged bean proteins are soluble to the extent of 60% at the pH of a meal-water slurry (pH 6.6), 80% at pH 11 but only 12% at pH 5. However, the proteins are soluble to the extent of 80% from pH 5 to 9 in 10% NaCl rising to 90% at pH 11. There are no satisfactory ways of recovering all the proteins from solution by simple changes in pH or ionic strength. Winged bean seed contains major proteins with sedimentation coefficients of 2 S and 6 S. Electrophoresis on cellulose acetate resolves three globulin fractions which we have named psophocarpins A, B, and C. The proteins from these electrophoretic regions have been isolated and partially purified. Psophocarpin A is essentially a single protein comparatively rich in sulfur-containing amino acids while the other fractions are composed of a number of related components which have not been separated. When examined by SDS-polyacrylamide gel electrophoresis, the globulin fractions differed in the kind of subunit proteins they contain and in the extent of disulfide bonding. The 40 000 mol. wt subunit of psophocarpin A contains disulfide bonded chains of mol. wt 16 000 and 24 000. The proteins corresponding to the other electrophoretic regions are more complex.

Proteases of germinating winged-bean (Psophocarpus tetragonolobus) seeds: purification and characterization of an acidic protease

“…With the realization that this crop could be as important as soya bean, particularly in the humid tropics [14], extensive studies were carried out to characterize the storage proteins, lectins and protease inhibitors of this plant by various groups, including ours [15][16][17][18][19][20][21][22]. We have previously presented the protein profile of the germinating seeds, but nothing is known about the proteases or the mechanism of storageprotein mobilization.…”

Biochemical basis of insect resistance in inged bean (Psophocarpus tetragonolobus) seeds

“…Not only have the winged bean seed proteins been separated into albumin and globulin type proteins, but they have also been separated, on the bases of their solubilities, into three fractions known as Psophocarpin A, B, and C (Gillespie and Blagrove 1978) (Fig 2). Their physiological concentrations within the mature seed are estimated to be 7,49 and 65 g kg-respectively.…”

Quality deterioration of winged bean during storage.

“…A report from the National Academy of Sciences (USA) has called attention to the need for research on this promising legume (1). Identification of major globulins in winged bean seeds has been done, and amino acid compositions of the proteins, fatty acids, and carbohydrates have been studied (2)(3)(4)(5). Our objective in the study presented here is to explore quality changes in winged bean seeds during storage and also to find the most desirable conditions for storage.…”