Cereal Chem 56:389 - 393.  |  VIEW ARTICLE
Extraction and Characterization of Rice Proteins.

V. W. Padhye and D. K. Salunkhe. Copyright 1979 by the American Association of Cereal Chemists, Inc. 

Protein content of 60-mesh, defatted rice (Oryza sativa L.) meal was 10.6% on a dry weight basis. Fractionation of rice proteins yielded albumin, globulin, prolamin, and glutelin in the proportions of 8:9.5:12.5:70, respectively. The ultraviolet absorption spectrum, amino acid composition, isoelectric points, and subunit constitution of proteins were distinctly different for each fraction. Nonoverlapping of isoelectric points and molecular weights of protein subunits suggested the absence of cross-contaimination between various fractions. The respective chemical scores of albumin, globulin, prolamin, and glutelin fractions were 47.5, 53.0, 23.0, and 46.7. Leucine. lysine, sulfur-containing amino acide, and threonine were the limiting amino acids of total proteins in rice with respective scores of 65.1, 66.3, 67.9, and 78.9. Estimates of biological values of protein fractions in human nutrition qualified albumins as superior and prolamins as inferior proteins. Two-dimensional slab gel electrophoresis, with phenol-acetic acid-mercaptoethanol-urea (PAMU) system in the first dimension and sodium dodecyl sulfate system in the second dimension indicated that the mobility of protein in PAMU may depend on its molecular size.