1988 Fiscal Year Final Research Report Summary
Studies on the separation of phospholipase A_2 preferred the arachidonoyl species of phospholipids
| Project/Area Number |
62580135
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
物質生物化学
|
|---|
| Research Institution | Faculty of Pharmaceutical Sciences, Teikyo University |
|---|
Principal Investigator |
NAKAGAWA Yasuhito Fac. Pharm. Sci., Teikyo University, Lecturer, 薬学部, 講師 (00119603)
|
|---|
| Project Period (FY) |
1987 – 1988
|
| Keywords | Macrophage / Arachidonic Acid / Phospholipase / Calcium / カルモデュリン |
|---|
| Research Abstract |
The effects of calmodulin antagonists on the amount of free fatty acid produced by alveolar macrophages exposed to opsonized zymosan were determined. Opsonized zymosan-induced free arachidonic acid (20:4) production was dramatically suppressed in the presence of W-7 and trifluoperazine without an effect on the production of other fatty acids. Calmodulin antagonists appeared to inhibit phospholipase A_2, since W-7 abolished the liberation of 20:4 from choline glycerophospholipids (CGP) and inositol glycerophospholipids (IGP$. After the challenge with opsonized zymosan, the 20:4 liberation caused by opsonized zymosan was significantly reduced in the absence of extracellular Ca^<2+>, indicating that the release of arachidonic acid required the influx of the extracelluler Ca^<2+> into cell. On the other hand, oleic acid and linoleic acid liberation from alveolar macrophages exposed to opsonized zymosan was not inhibited after the depletion of extracellular Ca^<2+>.
Most of phospholipase A_2 activity was present in the cytosol fraction of alveolar macrophages, representing 70% of the total activity. Calcium enhanced the hydrolysis of 16:0-20:4 GPC with cytosolic phospholipase A_2, although the phdrolysis of 16:0-18:1 and 16:0-18:2 species of CGP was not changed by calcium.
The purification of cytosolic phospholipase A_2 has been performed by using the hydrophordic column, ion exchange column and gel filtration column. However, phospholipase A_2 which selectively hydrolyzed the arechidonoyl species of phospholipids failed to be isolated.
The present studies indicate that phospholipase A_2 in rabbit alveolar macrophages is controlled by Ca^<2+> and calmodulin, and preferentially hydrolyzes arachidonic acid from phospholipids.
|
