STRUCTURAL-ANALYSIS OF GLOBULINS ISOLATED FROM GENETICALLY DIFFERENT AMARANTHUS HYBRID LINES

The main storage protein of Amaranthus species, the oligomeric salt-so luble globulin was isolated and purified to homogeneity from six genet ically different Amaranthus lines and compared with a previously inves tigated line i.e., Amaranthus K343. Physico-chemical analyses revealed that some heterogeneity existed with respect to the overall molecular weight of the globulins tested, as did differences in the molar ratio of their constituent (individual) subunits. Amino acid compositions o f these proteins were found to be very similar and characteristically high in aspartic/asparagine and glutamic/glutamine amino acids. Circul ar dichroic studies revealed that all globulins shared similar seconda ry structural conformations characterized by low alpha-helical and hig h beta-sheet contents. Although internal conformations were found to b e very highly conserved, tertiary structural analysis revealed that su bstantial differences existed in the arrangement/proximity and exposur e of aromatic amino acids on globulin surfaces. (C) 1998 Elsevier Scie nce Ltd. All rights reserved.