Isolation of endosperm protein and aleurone cell contents from wheat, and determination of their amino‐acid composition

Abstract

The techniques of air classification, and differential centrifugation in non-aqueous media, have been combined t o isolate from flour ( a ) endosperm protein and (b) aleurone cell contents. The amino-acid composition of the isolated protein has been determined and compared with that of the total protein complex in the parent flour. The results show that in the isolated protein fraction the proportion of the glutenin/gliadin group of proteins is higher than in the parent flour. This was observed in the material obtained from both a strong and a weak flour. It is suggested that this partial segregation occurs in the air classification process. The protein fractions isolated from the weak and strong flours were closely similar in their overall amino-acid composition. The amino-acid composition of the protein contained in the isolated alenrone cell contents has also been determined. The composition is quite different from that of the main endosperm proteins and resembles, in this respect, some of the soluble protein fractions which have been previously isolated from flour. A notable feature of the composition is a relatively high content of arginine.

Physiological Effects of Gibberellic Acid. VII. Electron Microscopy of Barley Aleurone Cells

“…Guillermlondl (8) (16,29), concentrations high enough to expect (liscrete organelles containing these constituents to he present. Figure 14 is a photograph of a portion of an aleurone grain of (iry barley fixed with osmium.…”

Comparative studies between the optimum dietary fibre sources of some substituted cookies

“…Whereas the improvement of lysine reached 17.0, 25.8 and 40.3% when CB, BH and RB at optimum level 7.9, 5.2 and 9.3% were supplemented to cookies, respectively, compared with unsupplemented cookies. The biological value of the protein in germ and aleurone is higher than that of the endosperm proteins; the lysine content is 2-2.5 times as large in protein of these tissues as it is in that of endosperm [22]. In fact, most of the decrease of amino acid values in tested high dietary fibre cookies lies in the essential rather than the nonessential amino acids with a total amino acids loss of the original sample as shown in Table 1.…”

Localization of Arginine-Rich Proteins in Mature Seeds of some Members of the Gramineae

“…Clair (1970) This modification of a variable-density procedure described by Stevens, McDermott, and Pace (1963) utilizes mixtures of chloroform-benzene and chloroform-tetrachloroethylene instead of carbon tetrachloride-benzene, and separation is accomplished in a large beaker under normal gravity conditions instead of by centrifugation. The starting material was obtained from the medium fraction of air-classified flour and the procedure yielded quite pure preparations of aleurone bodies and relatively intact aleurone cytoplasm when examined by light microscopy ( Fig.…”

“…Protein deposits in the aleurone layer of wheat contain basic protein (Oksijuk 1961(Oksijuk , cited in 13uttrose 1963 and amino acid analyses of isolated aleurone cell contents of wheat show a marked increase in basic amino acids, especially arginine, compared to endosperm protein (Stevens, McDermott, and Pace 1963). Coates and Simmonds (1961) have also isolated protein fractions from wheat flour which have a relatively high arginine content although the studies of Graham, Morton, and Raison (1963), Jennings and Morton (1963), and Morton, Palk, and Raison (1964) have not indicated that endosperm protein bodies are rich in arginine.…”