Electrophoresis SDS-PAGE and Tricine-SDS-PAGE to differentiate black and yellow soybean: a molecular approach

Abstract

Soybean is well recognized for having several bioactive compounds. Black soybeans have been used in Eastern countries as a healthy food and as an medicinal alternative. The identification of natural substances, such as peptides, present in black and yellow soybeans is necessary.  An evaluation of the contribution of these molecules to positive effects to human health molecular studies should be done. The search for molecular aspects that may explain this difference between black soybean and yellow soybean is extremely important.  In order to have a peptide-protein extract with semi-purified aspects for further molecular characterization, soybeans grains were grounded in a home-use coffee grinder and fat was removed by using acetone. The protein extracts obtained were characterized by two eletrophorectic techniques (SDS-PAGE and Tricine-SDS-PAGE).  Polyacrylamide gels with clear and well-defined polypeptide chains showed that both black and yellow soybean genotypes presented the peptide 5 kDa, while, the 4 kDa peptide was only found in black soybeans. This study, on molecular bases, showed that this method to obtain peptide-protein extracts was effective, to separate peptides in that region and could contribute to choose black or yellow soybean genotypes for clinical trials in evaluation of different health effects.