LOCALIZATION AND CHARACTERIZATION OF THE SORGHUM PROLAMIN, KAFIRIN (PROTEIN BODY (BODIES), SEED, ELECTRON MICROSCOPY, CHROMATOGRAPHY)

In the first part of this study, the localization of kafirin and cross-linked kafirin was investigated. Protein bodies were isolated from immature sorghum seeds. Then, proteins were extracted from the protein bodies. These proteins were compared to proteins extracted from flour of mature and immature sorghum seeds. The results of four types of analyses confirm that protein bodies in sorghum endosperm contain kafirin. The analyses included: acid urea polyacrylamide gel electrophoresis (AU-PAGE); polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE); amino acid analysis (AAA); and transmission electron microscopy (TEM). Sections of immature seeds prepared for TEM suggested that protein bodies in sorghum originate from the rough endoplasmic reticulum. Sections of mature sorghum seeds were treated sequentially with (zeta)-amylase, aqueous alcohol, and aqueous alcohol with a reducing agent to remove starch grains, protein bodies, and protein matrix. Results suggest that the protein matrix includes cross-linked kafirin as a component protein. In the second part of the study, the character of kafirin proteins was investigated. Several components of kafirin were separated by reverse phase high performance liquid chromatography and subjected to NH(,2)-terminal sequence analysis. There are three distinct types of sequence, two of which have highly conserved Ile-Pro-Gln and Pro-Pro sequences. One component of kafirin exhibited 66% homology within the first 30 residues to a zein sequence predicted from CDNA. The first 71 residues of a peptide approximately 194 residues in length have been delineated for another kafirin component called K8