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

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Abstract
Two groups of polypeptides, which together represented over 90% of the secalin fraction, were purified by ion exchange chromatography and gel filtration. These fractions had molecular weights of 40 000 and 75 000 by SDS-PAGE and 33 000 and 54 000 by sedimentation equilibrium ultracentrifugation respectively. Isoelectric focusing showed that each fraction contained a number of polypeptides. Amino acid analysis showed that the two groups had similar compositions with high glutamate + glutamine and proline and low lysine. The N-terminal sequences of the two groups were identical at 17 of the first 20 positions and were similar to those reported for γ2 and γ3-gliadins of wheat. Both groups had C-terminal histidine. These results are discussed in relation to prolamin evolution and homology in barley, rye and wheat.