Corn endosperm: protein distribution and amino acid composition in amylomaize vs. normal dent hybrid

Samples of maize homozygous for the recessive gene ae and its normal counterpart in the inbred line W64A background were analysed, together with a series of 3 high-amylose hybrids, each with starch of a different amylose content. The control hybrid was chosen as typical of that grown in the Corn Belt of America. Pericarp, germ and endosperm were separated. Total starch amylose and total N were estimated, also the amino acids in hydrolysates of the protein fractions. Commercial amylomaize hybrids had a higher proportion of saline-soluble protein glutelins, but a lower ethanol-soluble protein content than normal dent hybrid maize. Lysine was the only amino acid that differed significantly in the endosperm protein of the hybrids, ranging from 2.9 g/16 g N in amylomaize with 81% amylose to 1.6 g/16 g N in normal dent hybrid containing 28% amylose. The W64A ae strain contained twice as much amylose as its normal counterpart, but the other results did not differ significantly, showing that the ae gene has little effect on the composition of endosperm protein.<new para>ADDITIONAL ABSTRACT:<new para>Commercial amylomaize [high-amylose] hybrids had a significantly higher proportion of saline-soluble protein and glutelins and a lower ethanol-soluble protein content in the grain endosperm than (a) normal dent hybrid maize. Lysine content of endosperm protein ranged from 2.3 g/16 g N in class 5 amylomaize (62% amylose) to 2.9 g/16 g N in class 8 amylomaize (81% amylose) compared with 1.6 g/16 g N in (a) (28% amylose). Contents of other essential amino acids in amylomaize were also higher than those in (a). In contrast to amylomaize hybrids, endosperm proteins of the high-amylose inbred line W64Aae (61% amylose) were similar to those of the normal line W64A (32% amylose) with respect to both protein distribution and amino-acid composition.