Seed globulins of various species of cucurbitaceae

Globulins isolated from 6 species of the Cucurbitaceae family (C. maxima, C. pepo, C. moschata, Luffa cylindrica, Lagenaria vulgaris, and Momordica charantia) were studied. Nitrogen content of the globulins varied from 18.3 to 18.8%, with a mean of 18.6%. Of the individual amino acids, the most abundant were arginine and glutamic acid. Content of histidine, proline, serine, and tyrosine showed relatively higher variability within the group of species compared. MWs of the globulins, determined with Sephadex G 200, were 241 000 (C. maxima, C. pepo), 248 000 (C. moschata, L. cylindrica), 256 000 (L. vulgaris), and 218 000 (M. charantia). By ultracentrifugal analysis of globulins in 2 M NACl (pH 8), 3 fractions were identified in all the species except M. charantia, their sedimentation coefficients being in the range of (1) 5.2 S–7.2 S, (2) 15.3 S–17.2 S, and (3) 10.4–11.2 S. The latter fraction predominated in all the species, its amount was 94–96% of total globulins. Differences in electrophoretic properties of the globulins and their subunits produced in the presence of 8 M urea and by oxidative splitting with performic acid, respectively, and results of electrophoresis in SDS-acrylamide gels are also discussed.