Seed Proteins of Common Bean¹

Abstract

Fractionation of bean (Phaseolus vulgaris L.) cotyledon storage proteins using an improved separation procedure revealed a protein profile in which globulin‐I was the major fraction (about 40% of the total cotyledon protein), followed in importance by an alkali‐soluble fraction (about 25%) containing glutelin and albumin, free amino acids, ginbulin‐2, prolamine, and residue fractions. SDS‐acrylamideg el electrophoresis was performed to determine banding patterns of total cotyledon polypeptides and the purity of the fractions. Amino acid analyses using an autoanalyzer were performed on total protein and protein fractions. The alkali‐soluble fraction had the highest concentration of methionine (2% of the protein by weight), while the methionine percentage of globulin‐1 (0.88%) and albumin (1.0%) was less than that of the respective cotyledons (1.10%). The alkali‐soluble and globulin‐1 fractions comprised three‐fourths of the total cotyledon methionine. Total cotyledon protein was positively correlated with globulin‐1, free amino acids, alkali‐soluble, and globulin‐2 fractions. Significant positive correlations between amount of methionine in the cotyledons and that in the alkalisoluble fraction were also found. This finding suggests that selection for high protein genotypes in which the alkali‐soluble fraction is increased should result in improved methionine content. Since quantitative estimation of this fracion is time‐consuminga, simplified procedure for determining the amount of protein insoluble in ascorbate‐NaCl solution is suitable for identifying strains with large amountos f the alkali‐soluble fraction.

Expression of a methionine-rich storage albumin from the Brazil nut (Bertholletia excelsa H.B.K., Lecythidaceae) in transgenic bean plants (Phaseolus vulgaris L., Fabaceae)

“…However, although beans are rich in some essential amino acids, e.g., lysine, threonine, valine, isoleucine and leucine, their nutritional value is limited because of the small amounts of the essential amino acid methionine and cysteine (Ma and Bliss, 1978). One strategy to correct this deficiency is to introduce transgenes encoding a methionine-rich storage albumin from the Brazil nut (Bertholletia excelsa H.B.K., Lecythidaceae) into bean hosts.…”

Accelerated aging of ipê seeds under controlled conditions of storage

“…To make up the volume to 25 mL, distilled water was added, and the solution was then placed into water-bath with boiling water, for 5 min. A 20 µg sample of protein was applied to polyacrylamide gel SDS-PAGE at 15% (separator gel) and at 3% (concentrator gel) according to Laemmli (1970), and in agreement with changes performed by Ma and Bliss (1978). The electrophoretic system containing the samples were placed into a buffer solution with pH of 8.3 (50 mM Tris, 0.384 M Glycine, 5mM ethylenediaminetetraacetate (EDTA), pH 8.8 and 0.25% SDS).…”

Phaseolin: Structure and Evolution

“…As the major seed storage protein of French bean, it accounts for 50% of the total protein stored in the cotyledons [36], and 35-46% of the total seed nitrogen [12,55]. It is now rigorously established that spatial regulation of phaseolin expression is mandated through a combination of epigenetic [56,57,58] and genetic [46] events (chromatin structure and transcription factors).…”

“…The phaseolin direct repeat studies not only have important implications in phaseolin evolution, but in nutritional improvement of the French bean and legumes in general, as the sequence analysis of various phaseolin types make it possible to deduce potential sites for amino acid replacement to improve the overall methionine content of phaseolin [55,59]. Hall et al [26] also stated that a thorough characterization of the phaseolin sequence can be aimed at the ultimate goals of improving both in vivo and in vitro enzyme digestibility by eliminating the asparagine residues to which the Nglycans are linked and improving nutritional value by inserting additional methionine codons into the -phaseolin gene.…”