Analytical scanning isoelectrofocusing. 5. Separation of glycinin subunits in urea-dithiothreitol media

Physicochemical properties of oilseed proteins

This review attempts to consolidate the information on the physicochemical properties of proteins from groundnut, soybean, sesame seed, mustard seed, rapeseed, sunflower seed, cottonseed, and other oilseeds. It deals with the extraction and characterization of the oilseed proteins and describes the methods for isolation of the various protein fractions and determination of their physicochemical characteristics. Also discussed are the subunit composition of the oligomeric proteins, their hydrodynamic properties, and the effect of denaturants on these proteins. The similarity in the properties of the proteins from various oilseed materials is discussed. The review article aims to indicate the gaps in our knowledge about the physicochemical properties of oilseed proteins and suggests areas for future investigation.

Genetic variation in the subunits of globulin-1 storage protein of French bean

Charge and molecular weight heterogeneity of globulin-1 (G1) polypeptides of the bean, Phaseolus vulgaris L., were revealed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Different bean cultivars were classified into three groups: 'Tendergreen', 'Sanilac', and 'Contender' on the basis of their protein subunit composition. Nine distinct major bands: α51,α49, α48.5,β48(T), β48(S), β47, γ45.5, γ45(S), and γ45(C), and two minor bands: γ46(T) and γ46(S) were found to account for the three profiles seen on one-dimensional SDS-PAGE. Two-dimensional analysis revealed these eleven protein bands to be composed of a minimum of fourteen distinct protein subunits. The 'Tendergreen' and 'Sanilac' types differ in their G1 polypeptide composition. The protein patterns of the 'Contender' types are intermediate, containing many protein subunits found in the patterns of the 'Tendergreen' and 'Sanilac' types suggesting a genetic and evolutionary relationship.

Heterogeneity of human alpha-fetoprotein as revealed by isoelectric focusing in urea-containing gels

The heterogeneity of human alpha-fetoprotein has been studied by analytical isoelectric focusing in polyacrylamide gel slabs in the presence of 8 M urea. Six major isoelectric variants could be identified over a pH range of 6.0--6.2. Verification of their identity was achieved by crossed immunoelectrophoresis into agarose gel containing monospecific antiserum to human alpha-fetoprotein. Complete desialylation of the protein did not abolish the heterogeneity; a complex pattern of major alpha-fetoprotein bands persisted over a more alkaline pH range. We have been able to correlate the pattern of alpha-fetoprotein heterogeneity seen following extended agarose gel electrophoresis with that obtained during isoelectric focusing in the presence of urea. The quantity of certain alpha-fetoprotein charge isomers in various alpha-fetoprotein isolates may be important in considering certain biological functions of this protein.

Effects of diethylstilbestrol on the production of various extracellular products of Staphylococcus aureus

The synthetic estrogen diethylstilbestrol at a subinhibitory level of 1.75 microng/ml diminished the production of staphylococcal alpha toxin, coagulase, deoxyribonuclease and penicillinase. Thus, the reported host beneficial effects of diethylstilbestrol may be partially related to its retardive action of certain toxins, or enzymes of S. aureus.

Beta-conglycinin from soybean proteins. Isolation and immunological and physicochemical properties of the monomeric forms

Beta-conglycinin consisting of six major isomers (designated B1- to B6-conglycinin) was dissociated and fractionated on columns of DEAE- and CM-Sephadex in buffers containing 6 M urea. Three major (alpha, alpha' and beta) and one minor (gamma) subunits were isolated and further characterized by gel electrophoresis and gel electrofocusing. Gel electrophoresis in urea and in sodium dodecyl sulfate, and gel filtration in 6 M guanidine hydrochloride gave a molecular weight of 57 000 for alpha, alpha' subunits; and 42 000 for beta and gamma subunits. The isoelectric points of the isolated subunits, measured by disc gel electrofocusing, were as follows: alpha, 4.90; alpha', 5.18; beta, 5.66-6.00. On gel electrofocusing, beta subunit showed four microheterogeneous components; three of them comprised 95% of the total beta subunit. Leucine and valine were the N-terminal amino acids of beta and alpha alpha' subunits, respectively. The isolated subunits contained mannose and glucosamine in varying quantities. Two carbohydrate moieties were calculated for one mole of alpha, alpha' subunits; and one carbohydrate moiety for the beta subunit. Considerable similarity in the amino acid composition of alpha and alpha' subunits was observed. The beta subunit was devoid of cysteine and methionine; and in comparison with alpha, alpha' subunits, had a higher content of hydrophobic amino acids. The isolated subunits exhibited antigen-antibody reaction with antisera to the native beta-conglycinin. Each of them was partglycinins. The alpha and alpha' subunits were in addition identical with each other and with B5-, B6-conglycinins. They were immunologically unrelated with beta subunit. The recovery of immuno-properties from the individual subunits may be attributed to the reconstruction of the three-dimensional structure upon removal of denaturing reagents.