| Project/Area Number |
63480055
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
応用生物化学・栄養化学
|
|---|
| Research Institution | Nagoya University |
|---|
Principal Investigator |
MAKINO Shio Nagoya Univ., Fac. of Agric., Professor, 農学部, 教授 (80000842)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
MORIYAMA Ryuichi Nagoya Univ., Fac. of Agric., Associate, 農学部, 助手 (60191061)
|
|---|
| Project Period (FY) |
1988 – 1989
|
| Project Status |
Completed (Fiscal Year 1989)
|
| Budget Amount *help |
¥4,700,000 (Direct Cost: ¥4,700,000)
Fiscal Year 1989: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1988: ¥3,000,000 (Direct Cost: ¥3,000,000)
|
|---|
| Keywords | Glycinin acidic subunit / Bile acid-binding protein / Insulin-stimulating peptide / Stimulation of fat decomposition / Inhibition of insulin degradation / 胆汁酸結合大豆タンパク質 / 大豆グリシニン酸性サブユニット |
|---|
| Research Abstract |
Several lines of evidence had indicated that some component(s) of soybean protein participates in the modulation of lipid metabolism and that one of the hormones involved in the metabolism is insulin. We looked for soybean protein component(s) which is capable of affecting the insulin action. By sequencing of purified peptides and examination of their effects on fat decomposition in isolated rat adipocytes, it was confirmed that A_<1a> and A_2 acidic subunits of glycinin potentiate the action of insulin in vitro. In addition, the proteins showed an ability to bind bile acids. Thus, these proteins are probable candidates which exert the hypocholesterolemic effect, a well-known physiological function of soybean protein, by interfering with steroid adsorption. However, the bile acidbinding ability was not related to the insulin-stimulating activity. Both properties were noted in acidic subunits of legumin from pea seed, indicating that these characteristics may be common to legume proteins.
Trypsinized products of A_<1a> subunit (A_<1a>/TR) also exhibited the insulin-stimulating activity and the molecular mechanism was examined by using rat adipocytes. A_<1a>/TR did not affect the glucose transport, which is the primary process of insulin action on the cells.
However, A_<1a>/TR enhanced a reactivity and a sensitivity of fat decomposition to insulin.
Affinity of insulin to its receptor on the cell surface was not affected by A_<1a>/TR. A_<1a>/TR protected insulin from degradation, resulted in an increase of insulin concentration in the cells. The insulin-stimulating activities were not observed at 15ﾟC, indicating that the internarization of insulin is requisite for an appearance of the protein effect, and the inhibition of insulin degradation alone cannot account for the enhancing effect observed in the maximal responses to the hormone.
|
