Isolation and quantitation of zeins in waxy and amylose-extender and wild flint and dent maize endosperm using a new solvent sequence for protein extraction

Protein distribution in endosperm of maize grains differing by their textur e, flint or dent, and by their genotype, wild or waxy or amylose-extender, was examined by the successive use of 0.5 M NaCl, 0.5 M NaCl plus 0.6% 2-me rcaptoethanol (2ME) at neutral and then alkaline pH, and 55% 2-propanol plu s 0.6% 2ME as extractants. Proteins extracted in the presence of 2ME were c haracterized by their size polymorphism and amino acid composition. Protein s isolated with NaCl plus 2ME at neutral pH corresponded with a mixture of gamma -zein (27 kDa) arid glutelin-like proteins. Proteins isolated with Na Cl plus 2ME:at pH 10 were a mixture of gamma -zeins (27 and 16 kDa) and bet a -zeins (14 kDa). Alcohol-soluble proteins consisted of alpha-, beta-, and delta -zeins, alpha subunits being predominant. Zein quantitation was impr oved by weighing the nitrogen percentage of extracts by their zein content, as estimated from the data on amino acid composition. The data reported by Wolf et al. (Cereal Chem. 1975, 52, 765) were integrated to the results of this work to suggest the occurrence of an inverse correlation between amyl ose in starch and zeins in proteins.