Cereal Chem 50:383 - 394.  |  VIEW ARTICLE
The Effect of the Floury-2 Gene on the Distribution of Protein Fractions and Methionine in Maize Endosperm.

L. W. Hansel, C.-Y. Tsai, and O. E. Nelson. Copyright 1973 by the American Association of Cereal Chemists, Inc. 

The proteins of floury-2 (fl2) endosperm contain about 60% more methionine than normal on a weight basis and little or no difference on an endosperm basis. Two main factors contribute to the increased methionine in fl2 endosperm: the increase in methionine content of the fl2 glutelins, and the shift of the zein-glutelin protein ratio. Based on total protein, zein decreases from 57 to 32%, and glutelin increases from 31 to 44% in fl2 relative to normal. The major sources of methionine in each genotype are the zeins and glutelins. In normal, the zeins and glutelins account for 55 and 40% respectively, of the total methionine. In fl2 the values are zeins, 22%, and glutelins, 74%. The remaining percentage in each genotype is distributed among the albumins, globulins, and the nonextractable residue. Twenty-four subfractions are obtained following the fractionation of the Osborne fractions and their components on Sephadex. The results show that quantitative shifts in proteins occur in each of the fractions and components. However, there are no new or missing subfractions in fl2 compared to normal. The distribution of N-terminal methionine is found to coincide generally with the distribution of total methionine. The contribution of N-terminal methionine by each genotype is small, comprising about 1.5% of the total methionine. The fractionation results, in conjunction with the methionine results, show that the gene substitution at the fl2 locus generally increases production of proteins with a higher methionine content and suppresses synthesis of the proteins with a lower methionine content, and that the fl2 mutation does not increase methionine by increases in N-terminal methionine residues.