Sorghum protein ultrastructure as it relates to composition

Abstract

The ultrastructure of endosperm protein from 7 habrids and 8 experimental lines was studied with both transmission and scanning electron microscopes. Vitreous endosperm shows a well-developed 2-component structure consisting of protein bodies embedded in a matrix protein. The aqueous alcohol-soluble fraction (prolamine) proved to be the major component of globular protein bodies. The surrounding matrix protein consisted mostly of glutelin. Globular protein bodies have a nuclear that is insoluble in aqueous alcohol. Protein bodies of almost all grain sorghums were 2-3 μm, in diam. One experimental line with above average lysine content had smaller protein bodies, a condition which verifies the negative correlation between prolamine and lysine. Distribution of protein within the sorghum kernel is similar to that of other cereal grains. The peripheral vitreous area of the kernel is rich in protein; interior areas have smaller amounts of protein. Microscopic observations show that protein bodies make up the major part of sorghum endosperm protein.