Abstract: Northeastern Chinese soybeans are one of the most important genetic resources in the world. In order to use them effectively in soybean breeding, it is necessary to evaluate the main characteristics, especially the quality characteristics such as seed protein content. It is reported that the PEPCase activity in soybean seeds is positively correlated with the seed protein content and negatively correlated with the lipid content^[1].PEPCase is also present in seeds of different species^[2-4],and may play an important role in amino acid biosynthesis. PEPCase was detected in the protein bodies of developing wheat grains, possibly contributing to storage-protein bodies of developing wheat grains,possibly contributing to storage-protein biosynthesis^[5]. A strong correlation between PEPCase activity and protein concentration in seeds of 13 soybean cultivars^[1] indicates a possible rate-limiing role of the enzyme in seed storage-protein accumulation. In soybean, PEPCase is encoded by a small family of at least four highly homologous genes^[6] and PEPCase catalyzes the carboxylation of phosphonenopyruvate to oxalacetic acid, which increases the number of carbon skeletons of amino acids.