Partial characterization of tannin-protein complexes in five varieties of grain sorghum by automated gel filtration chromatography.

Abstract

1st-moment apparent mol. wt. (M) for the glutelin fraction of 5 cv. of grain sorghum were determined by gel chromatography with detection by UV absorbance at 254 and 206 nm. For the low-tannin cv. SC 301, CK 60 and TX 615, M based on absorbance at either wavelength was about 1.7 X 103. For the intermediate-tannin cv. NSA 740, M was 1.82 X 103 when based on detection at 206 nm and 2.21 X 103 when based on 254 nm, whereas the high-tannin cv. GA 615 had values of 0.90 X 103 and 2.36 X 103 at 206 and 254 nm, resp. The higher values of M at 254 nm for intermediate- and high-tannin cv. compared with low-tannin ones were attributed to higher levels of protein-tannin complexes which have higher extinction coefficients at 254 than at 206 nm for mol. wt. in excess of 2500. This conclusion was supported by the measurement of tannin and protein content in the glutelin fraction