The Purification and Characterization of Two Groups of Storage Proteins (Secalins) from Rye (Secale cereale L.)

Two groups of polypeptides, which together represented over90% of the secalin fraction, were purified by ion exchange chromatographyand gel filtration. These fractions had molecular weights of40 000 and 75 000 by SDS-PAGE and 33 000 and 54 000 by sedimentationequilibrium ultracentrifugation respectively. Isoelectric focusingshowed that each fraction contained a number of polypeptides.Amino acid analysis showed that the two groups had similar compositionswith high glutamate + glutamine and proline and low lysine.The N-terminal sequences of the two groups were identical at17 of the first 20 positions and were similar to those reportedfor ₂ and ₃-gliadins of wheat. Both groups had C-terminal histidine.These results are discussed in relation to prolamin evolutionand homology in barley, rye and wheat.