BIOCHEMICAL AND IMMUNOLOGICAL INVESTIGATIONS ON VEGETATIVE STORAGE PROTEINS OF TAXODIACEAE SPECIES

Vegetative storage proteins were investigated in the wood and bark of the Taxodiaceae Metasequoia, Sequoiadendron and Taxodium. In the wood of the deciduous Metasequoia glyptostroboides and the evergreen Sequoiadendron giganteum, prominent proteins were detected by SDS-PAGE during the dormant period, which showed strong seasonal fluctuations. The apparent molecular weights' of these vegetative storage proteins are 34 kD and 32 kD in the wood of Metasequoia (Sp-M34, SP-M32) and 32 kD and 30 kD in the wood of Sequoiadendron (SP-S32, SP-S30). A specific antibody raised against the 35 kD storage protein of Taxodium distichum wood (SP-T35) showed clearcut cross-reactions with SP-M34, SP-S32 and SP-S30. In the bark of the three Taxodiaceae species, prominent proteins corresponding in molecular weight to the respective wood storage proteins of these species were detected in January. These proteins clearly react with the SP-T35 antibody as well, indicating similarities between these wood and bark storage proteins. After peptide mapping with V8-protease from Staphylococcus aureus, SP-T35, SP-M34, SP-S32 and SP-S30 each show a degradation product of 19 kD in the protein pattern visible after SDS-PAGE. All the storage proteins detected are glycosylated. After enzymatic deglycosylation with N-glycosidase F, both SP-T35 and SP-M34 showed a 32 kD protein band. These 32 kD protein bands lack ConA binding although they still show a clearcut reaction with the antibody produced against SP-T35. This strongly suggests that the antibody reacts with the peptide moiety of the glycoproteins and not exclusively with the oligosaccharide chains. Analysis of the oligosaccharide chains of SP-T35 and Sp-M34 by different lectins showed that <<high mannose>> as well as complex sugar chains are bound to the apoproteins. By immunogold labeling, the 34 kD protein of Metasequoia could be located in so-called protein storage vacuoles in the ray parenchyma cells of the wood.