Improvement of food functions of soybean glycinin by protein engineering and transformation of modified glycine genes into tobacco.

点击翻译按钮获取中文摘要

Improvement in nutritional value and functional properties of plant proteins is attracting the attention for their potential in relieving the problem of both starvation and nutritional diseases. In order to establish. fundamental theory to develop novel soybean plants which produce improved proteins, improvement of food functions of soybean glycine by protein engineering and generation of transgenic tobacco plants which are transformed with modified glycine genes were attempted.1. The A_<1a>B_<1b> proglycinin cDNA was modified by insertion of synthetic DNAs encoding four continuous methionines to the cDNA regions corresponding to the variable domains and by deletion of each variable domain or disulfide bonds. The design strategy was based on the structural characteristics of glycine and the relationships between the structure and the functional properties of glycinin. The modified glycines expressed from the modified cDNAs in Escherichia coli were purified, and their abilities to form … More the correct conformation and their functional properties were investigated. Most of the modified glycinins having the abilities to form the correct conformation-exhibited better functional properties than the hative soybean glycinin.2. Investigation on the properties of the modified glycinins with the combination of the modifications described in 1 indicated that the modifications introduced into the glycinin do not induce wrong conformation at all. We can expect that those modified-combined glycinins may exhibit better functional properties than the modified glycinins.3. It was suggested that the yeast expression system of glycinin EDNA is useful for studying protein engineering of glycinin, because yeast can accumulate the modified glycinin containing a modification which disturbs the correct folding.4. The modified glycinin cDNAs encoding the proteins exhibiting high quality of food functions were transformed into tobacco cells using Ti plasmid system and transgenic tobacco plants were regenerated. The modified proteins were accumulated in some tissues of tobacco plants. Less