Screening of Lysine-rich Plant Species and Identification of the Purified Proteins

The nutritional quality of seed proteins from cereals, such as wheat and rice, is comparatively low due to its deficency in lysine and some essential amino acids. In this research extensive varieties of plant seed samples were collected and screened by analysis of amino acid composition. Three lysing-rich species which contain more than 6.7% of lysine in total seed proteins were found. 31 kinds of proteins were purified from a species which contains 7.9% of lysine using the modified methods of IEF and SDS electrophoresis. One protein with PI 6.1 and 18 kD was identified which contains 11.4% of lysine and was rich in threonine, valine and isoleucine. This is the first example of the protein which could complement several limiting amino acids of wheat or rice. Further research on the structural gene encoding this protein would have great potential value for improvement of protein quality of these cereals.