Albumin and globulin proteins of wheat flour: Immunological and N-terminalsequence characterisation

Several non-storage proteins are encoded by genes on individual wheat chrom osomes and these have been used as genome-specific markers. In this study, a library of monoclonal antibodies with differing specificities to water- a nd salt-soluble proteins has been developed in order to obtain markers for different wheat chromosomes. Two antibodies, BCSAU 9D1 and JGM 1B4 were fou nd to bind polypeptides encoded by chromosomes 3D and 7D respectively. Othe r antibodies bound to small numbers of polypeptides encoded by more than on e chromosome. such as 5A, 7D, 5B and 5D. The proteins recognised by some of the antibodies were isolated by immunoaffinity chromatography, and one pro tein was identified as an alpha-amylase inhibitor by N-terminal sequence ch aracterisation. In addition, 16 water-soluble and eight salt-soluble protei ns were isolated using SDS-PAGE, isoelectric focusing, two-dimentional elec trophoresis and reversed-phase high performance liquid chromatography with the main objective being to confirm the identity of particular proteins, es pecially those which were able to be assigned to particular chromosomes. Th e N-terminal sequencing characterisation identified 19 proteins, whereas fo ur proteins were found to be blocked and one did not match with any protein s in the database. Most of the water-soluble proteins belonged to a family of alpha-amylase inhibitors. One protein, assigned to chromosome 4BS, was h omologous to serine carboxypeptidase III. N-terminal sequences of some of s alt-soluble proteins matched with internal sequences of barley embryo globu lin. Other proteins were identified as lipid transfer protein, peroxidase B P-I precursor and histone H4 proteins. The protein sequences could also pot entially used for making antibody or DNA probes for use in selection in bre eding programmes. (C) 2001 Academic Press.