Steve Van Scoyoc’s research while affiliated with Purdue University West Lafayette and other places

Several parameters of the vanillin assay were examined to determine which must be most closely controlled to ensure accuracy and reproducibility. A 20-min extraction in methanol was found to be adequate. When corrected for background color, the modified vanillin assay was found to give nearly identical values with those obtained with the regular vanillin assay, except with group II sorghum. The reactions of tannin and catechin, the usual standard, with vanillin were found to differ markedly in reaction kinetics. Assays of purified tannin showed that use of catechin equivalents overestimates tannin content The assay was found to be extremely temperature dependent. Revised procedures for the vanillin assay are presented which give excellent reproducibility.

The purpose of this paper was to study the characteristics of proteins from normal, high lysine, and high tannin Sorghum bicolor (L.) Moench. Endosperm preparations were obtained from four inbred lines of sorghum representing a normal, low tannin variety (P-721-N), its mutagenically derived high lysine counterpart (P-721-0), an inbred Ethiopian variety high in lysine (IS-11167), and a high tannin line (IS-4225). Endosperm proteins were separated into five soluble fractions by the Landry-Moureaux method. Whole endosperms and their respective protein fractions were subjected to amino acid analysis. Polyacrylamide gel electrophoresis patterns were determined for the fractionated proteins. The high lysine endosperms had lower levels of kafirins (fractions II and III) than the lysine-deficient, alcohol-soluble protein fraction, when compared with the normal sorghum endosperm preparations. Both high lysine varieties contained elevated levels of albumins and globulins (fraction I) and glutelins (fraction V), which were the highest in lysine content. Differences from normal were observed in the distribution pattern of proteins from a high tannin sorghum. There were no significant differences among the constituent proteins of the identical fractions of these four varieties of sorghum as determined by gel electrophoresis. These results support the general hypothesis that genes affecting protein quality do so by changing the relative quantities of Landry-Moureaux fractions and not by changing the quality of proteins within these fractions.