1994 Fiscal Year Final Research Report Summary
The 3-D Structure and Reaction Mechanism in The Highly Organized supra-Molecule of Pyruvate Dehydrogenase Complex.
| Project/Area Number |
04454581
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
結晶学
|
|---|
| Research Institution | Tokyo Institute of Technology |
|---|
Principal Investigator |
TAKENAKA Akio Tokyo Institute of Technology, Associate Professor Department of Life Science, 生命理工学部, 助教授 (80016146)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
MATSUMOTO Osamu Tokyo Institute of Technology, Assistant Professor Department of Life Science, 生命理工学部, 助手 (10231599)
|
|---|
| Project Period (FY) |
1992 – 1994
|
| Keywords | Lipoamide dehydrogenase / X-ray analysis / Pyruvate dehydrogenase complex |
|---|
| Research Abstract |
The pyruvate dehydrogenase complex is one of the highly organized multienzyme system, consisting of multiple copies of three component enzymes, pyruvate dehydrogenase (E1), dihydrolipoyl acetyltransferase (E2), and lipoamide dehydrogenase (E3), which catalyses the irreversible serial reactios specifically and efficiently. The complexes are classified into two types of the central core structures composed of E2s with different symmetries depending on organisms. One has the 432 symmetry in Gram negative bacteria and the other the 532 symmetry in Gram positive bacteria and in eukaryotes. The cyustal structure of the isolated component of E3 from yeast was determined for the latter type. It has been found that there are two types of crystals which are different with each other in crystal habit. The crystal structures were solved by the molecular replacement method. The initial phases were improved by averaging and flattening of electron density map. The atomic coordinates of the molecular model constracted by FRODO were refined by XPLOR with a constrain of non-crystallographic 2-fold symmetry. Although the molecular packings are different, but the molecular structures are similar. Closer comparison with glutathion reductase indicated that although the large atomic deviations are observed in the C-terminal domain, the active site between the two domains has almost the same 3-D structure. This similarity is also observed in E3 from the different organisms with 432 symmetry. From the present investigation, it has been thus revealed that the tertiary structures of E3s are essentially the same even in the different architecture between the two types. It is noticed that such a strong conservation of the structure may be the functional restrain by the enzyme.
|
