Zein composition in hard and soft endosperm of maize

Maize protein composition and distribution may directly influence endosperm texture and physical properties. To test this hypothesis, we compared compositions of alcohol-soluble proteins in maize endosperm from the hard and soft fractions of eight normal genotypes. Kernels were hand-dissected to obtain fractions differing in texture. Endosperm fractions were extracted with a solution containing alcohol, reducing agent, and sodium acetate and were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by reversed-phase high-performance liquid chromatography. We found more (an average of 3.3 times more) alpha-zeins (19 and 22 kDa) in hard endosperm fractions than in soft endosperm fractions, In contrast, soft endosperm fractions contained nearly twice as much 27-kDa gamma-zein (based on percent) than did hard endosperm fractions. Thus, distribution of the various types of zeins was not uniform throughout the maize endosperm. Our results suggest that the zein composition of protein bodies in normal maize kernels may be correlated with texture of the endosperm from which the sample was obtained.