CHARACTERIZATION OF RAPESEED MYROSINASE-BINDING PROTEIN

Myrosinase-binding proteins (MBPs) were purified from seeds of Brassic a napus L. (oilseed rape). The proteins were characterized with respec t to amino-acid composition, peptide sequence and isoelectric points. Gel electrophoresis and Western blotting of protein extracts from matu re seeds showed the existence of at least ten proteins reacting with a monoclonal anti-MBP antibody and ranging in molecular size from 110 t o 30 kDa. Proteins other than MBP reacting with the anti-MBP antibody were assigned as myrosinase-binding protein-related proteins (MBPRPs). Two MBPRPs were purified by immunoaffinity chromatography and charact erized with respect to partial amino-acid sequence. Sequence identitie s were found between MBP and MBPRP. Western blot analysis of protein e xtracts from different tissues of B. napus showed that MBPRP is presen t in the whole plant, whereas MBP mostly occurs in the mature seed. A double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was used to investigate the occurrence of MBP and MBPRP in developing see ds of some species in the Brassicaceae family.