| Project/Area Number |
11680637
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Functional biochemistry
|
|---|
| Research Institution | University of Tokushima |
|---|
Principal Investigator |
MOTOKAWA Yutaro University of Tokushima ; Institute for Enzyme Research ; Professor, 分子酵素学研究センター, 教授 (40004585)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
IKEDA Kazuko University of Tokushima ; Institute for Enzyme Research ; Research Associate, 分子酵素学研究センター, 助手 (10108863)
|
|---|
| Project Period (FY) |
1999 – 2000
|
| Project Status |
Completed (Fiscal Year 2000)
|
| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2000: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1999: ¥2,900,000 (Direct Cost: ¥2,900,000)
|
|---|
| Keywords | lipoic acid / lipoate activating enzyme / lipoyltransferase / lipoyl-GMP |
|---|
| Research Abstract |
In mammals, lipoate-activating enzyme (LAE) catalyzes the activation of lipoate to lipoyl-nucleoside monophosphate. The lipoyl moiety is then transferred to the specific lysine residue of lipoate-dependent enzymes by the action of lipoyltransferase. We purified LAE from bovine liver mitochondria to apparent homogeneity. LAP activated lipoate with GTP at a 1000-fold higher rate than with ATP.The reaction absolutely required lipoate, GTP, and Mg^<2+> ion, and the reaction product was lipoyl-GMP.LAE activated both R- and S-lipoate to the respective lipoyl-GMP although preference for R-lipoate was observed. Similarly, lipoyltransferase equally transferred both R- and S-lipoyl moiety from respective activated lipoate to apoH-protein. Interestingly, however, only H-protein carrying R-lipoate was active in the glycine cleavage reaction. cDNA clones encoding a precursor LAE with a mitochondrial presequence were isolated. Amino acid sequence of LAE is identical with that of xenobiotic-metabolizing/medium-chain fatty acid : CoA ligase-III, but an amino acid substitution due to a single nucleotide polymorphism was found. These results indicate that the medium-chain acyl-CoA synthetase in mitochondria has a novel function, the activation of lipoate with GTP.
|
