Comparative Studies on the Proteins From Seeds of Lupinus angustifolius L.

Abstract

The seeds of 99 genotypes of L. angustifolius were examined by electrophoresis on cellulose acetate and found to contain two major salt-extracted globulins, conglutins α and β, and a third minor globulin, conglutin γ. Dissociation with sodium dodecyl sulfate and electrophoresis on polyacrylamide gel showed variation in the number, proportion and molecular size of the subunits which constitute these proteins. This was confirmed by electrophoresis in polyacrylamide gel containing urea at acid pH. The globulins in the salt extracts of some of the seeds were subject to partial enzymic degradation unless conditions which inactivate proteolytic enzymes were used during extraction. Crude protein level of the seed meal, determined for many of the genotypes from their nitrogen content, varied from about 30 to 50%. Only 5-10% of this total protein was water-extracted albumins. Amino acid analysis showed that the albumin fraction contains higher levels of many of the essential amino acids including cystine and particularly methionine.