Two protease inhibitors from Cajanus cajan seeds have been purified to homogeneity by trichloroacetic acid (TCA) solubilisation, ion-exchange and gelfiltration chromatography followed by preparative polyacrylamide gel electrophoresis. One of the inhibitors, Cajanus trypsin-chymotrypsin inhibitor (CTCI), inhibits both bovine trypsin and chymotrypsin while the other, Cajanus trypsin inhibitor (CTI), inhibits only bovine trypsin. The two inhibitors contained no carbohydrate and had an isoelectric point of 6. CTCI and CTI had average molecular weights of 15000 and 10500, respectively. The purified inhibitors in solution were stable to heat at 80°C for 15 min and pH 7-10. In the pH range 3-5, 80% of the activity was retained. Autoclaving totally destroyed the inhibitor activity. CTCI had two sites for trypsin binding and one site for chymotrypsin binding while CTI had only one site for trypsin binding. The inhibitors were very specific towards mammalian serine proteases and did not inhibit other proteases or serine proteases of bacterial origin.
Esterase isozymes were studied in seed extracts of Cajanus cajun and six Atylosia species by polyacrylamide gel electrophoresis and isoelectrofocusing. The isozyme patterns were stable and accession specific. Within the accessions of the Atylosia species, A. albicans and A. scarabaeoides showed three common bands indicating that they are more closely related to each other than to the other species. Of the accessions of Atylosia only A. cajunifolia shares the esterase isozyme of C. cajan and hence seems to be the closest wild relative of C. cajan.
Summary
The legumins of Pisum and Vicia have been compared and the proteins have been shown to differ in molecular weight, subunit molecular weights and amino acid composition. Legumin of Pisum however has a similar disulphide bridged subunit construction to that of Vicia and consists of basic (pI's greater than 7) and acidic subunits (pI's less than 7). Of the two molecules, Pisum legumin was shown to be more acidic at pH values of neutral and above. The protein from Pisum has all the antigenic determinants of Vicia legumin and one or more determinant groups in addition.
Tryptic peptide maps indicate that legumin is an homologous protein in Vicia and Pisum.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.