2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

The storage proteins of rye, called secalins, comprise four major groups of proteins, three of which are closely related to protein groups of wheat. HMW-secalins are related to HMW subunits of wheat glutenin, omega-secalins to omega-gliadins and gamma-40k-secalins to gamma-gliadins. The fourth group of secalins, the gamma-75k-secalins, has not yet been widely studied. Therefore, two gamma-75k-secalins were isolated from the rye cultivar Danko by Osborne fractionation and, subsequently, by RP-HPLC. Amino acid analysis of gamma-75k-secalins revealed significantly higher contents of Gln and Pro compared with gamma-40k-secalins and gamma-gliadins. MALDI-TOF mass spectrometry indicated molecular masses of about 52,000. N-terminal amino acid sequences were homologous with those of gamma-gliadins with the exception of position 5 (Asn) and position 12 (Cys). Further amino acid sequences were determined after enzymic digestion and separation of peptides by RP-HPLC. The C-terminal domain of gamma-75k-secalins showed a strong homology with gamma-gliadins and contained all Cys residues known from gamma-gliadins. The N-terminal domain of gamma-75k-secalins had a molecular mass of about 36,000 and, thus, is much longer than that of gamma-gliadins. It is characterized by repetitive sequences with a high content of Gln and Pro. Moreover, at least one Cys residue is present in the N-terminal domain explaining the aggregative character of gamma-75k-secalins.