Characterization of the proteins from Vigna unguiculata seeds.
The proteins from Vigna unguiculata (L.) Walp. (cowpea) seeds were investigated. Globulins constitute over 51% of the total seed protein, with albumins composing approximately 45%. The globulins may be fractionated by native electrophoresis or anion exchange chromatography into three main components, which were termed (in decreasing order of anodic mobility) alpha-vignin, beta-vignin, and gamma-vignin. alpha-Vignin, with a sedimentation coefficient of 16.5S, is a major, nonglycosylated globulin, composed of a major 80 kDa subunit, which upon reduction, produces two polypeptides (20 and 60 kDa). beta-Vignin, with a sedimentation coefficient of 13S, is a major, glycosylated globulin, composed of two main polypeptides (55 and 60 kDa) with no disulfide bonds. Finally, gamma-vignin, a minor globulin, is composed by one main type of subunit (22 kDa), which upon reduction, is converted into a single, apparently heavier polypeptide chain (30 kDa) due to the presence of an internal disulfide bond. Immunological analyses revealed structural homology between beta-vignin and beta-conglutin (the vicilin from Lupinus seeds) but not between alpha- or gamma-vignins and their Lupinus counterparts. Haemagglutination activity toward trypsinized rabbit erythrocytes was found exclusively in the albumin fraction and was strongly inhibited by N-acetylglucosamine or chitin.
Freitas
Regina L
RL
Departamento de Botânica e Engenharia Biológica, Instituto Superior de Agronomia, Universidade Técnica de Lisboa, 1349-017 Lisboa, Portugal.
Teixeira
Artur R
AR
Ferreira
Ricardo B
RB
D000418:Albumins / Q000737:chemistry / Q000302:isolation & purification; D007887:Fabaceae / Q000737:chemistry*; D005916:Globulins / Q000737:chemistry / Q000302:isolation & purification; D006031:Glycosylation; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification*; D012639:Seeds / Q000737:chemistry*
D000418:Albumins; D005916:Globulins; D010940:Plant Proteins