Characterization of Amaranth (Amaranthus hypochondriacus L.) Seed Proteins

Amaranth seed has a high nutritional value due to the balanced amino acid composition of its proteins. These were isolated by sequential extractions. The percentage concentrations of albumins, globulins, prolamins, and glutelins were 51.0, 15.9, 2.0, and 31.1, respectively, of total protein extracted, the insoluble fraction being quantitatively negligible. Albumins are the richest in sulfur amino acids (4.4 %), globulins in lysine (7.0%), and prolamins in leucine (10%) and threonine (7.2%). Glutelins are the poorest in lysine (4.2%). Upon electrophoresis, albumins were found to be the most polymorphous, while prolamins were made up of fewer and less abundant components. Two-dimensional gel electrophoresis analysis revealed the occurrence of some glutelins as the major proteins in the seed. In sucrose gradients, the albumins sediment in a major component ranging between 1.4S and 2.0S and a minor one of 4.6S. Globulins sediment in three components of 1.9S, 8S, and 13S.