Chemical and physicochemical characterization of CB-1a, an allergenic fraction isolated from castor bean (Ricinus communis L.).

CB-1A chemical characterization comprised the determination of nitrogen (Kjeldhal: 15.5%: amino acid composition: 17.5%), total (6.8%) and reducing (1.6%) carbohydrates, amino acid composition (Lys4, His1, Arg11, Asp3, Thr1, Ser7, Glu16, Pro2, Gly5, Ala3, Cys6, Val3, Met1, Ile3, Leu4, Tyr1, Phe1; 82 residues). Its behaviour under several TCA concentrations, ultraviolet absorption of native and oxidized CB-1A under several solvents as well as its enzymatic susceptibility were explored. Physicochemical parameters such as MW (protein moiety - composition: 9.642 Da, column: 9.431 Da: glycoprotein-10.345) Da; E1%1cm,220mm = 49.7 E1%1cm,595mm = 29.7: partial specific volume (anhydrous: 0.703 cm3/g; hydrated; 0.924 cm3/g); Stokes radius (15.1 A); hydration water (22%) and frictional ratio (1:10) were determined. Calculated limit molecular dimensions (semi-axis of revolution: 11.4 to 19.8 A) and equatorial radius (13.2 to 17.5 A suggest dendency to sphericity. CB-1A showed allergenicity by PCA. Fourteen components were detected by IEF.