1997 Fiscal Year Final Research Report Summary
STRUCTURAL AND FUNCTIONAL ANALYSES OF PHOTOSYNITHETIC ANTENNA COMPLEXES BY SCATTERING METHODS
| Project/Area Number |
08455377
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
生物・生体工学
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
WANG Zheng-Yu TOHOKU UNIVERSITY,GRADUATE SCHOOL OF ENGINEERING,DEPARTMENT OF BIOCHEMISTRY AND ENGINEERING,ASSOCIATE PROFESSOR, 大学院・工学研究科, 助教授 (10213612)
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| Co-Investigator(Kenkyū-buntansha) |
KOBAYASHI Masayuki TOHOKU UNIVERSITY,GRADUATE SCHOOL OF ENGINEERING,DEPARTMENT OF BIOCHEMISTRY AND, 大学院・工学研究科, 助手 (70271864)
NOZAWA Tsunenori TOHOKU UNIVERSITY,GRADUATE SCHOOL OF ENGINEERING,DEPARTMENT OF BIOCHEMISTRY AND, 大学院・工学研究科, 教授 (10006322)
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| Project Period (FY) |
1996 – 1997
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| Keywords | PHOTOSYNTHESIS / SMALL-ANGLE SCATTERING / PIGMENT / LIGHT-HARVESTING COMPLEX / AGGREGATE / PHOTOSYNTHETIC / BACTERIUM / ENERGY CONVERSION |
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| Research Abstract |
In the first year, small-angle scattering measurements were made to determine the size of smaII aggregates of bacteriochlorophyll (BChl) a and c formed in nonpolar soIution. Both BChl a and c form dimers and oligomers in equilibrium with each other at high concentrations in benzene-d<@D26@>D2 solutions. The size and molecular weight for each dimer have been quantitatively evaluahd based on Guinier approximation. The radii of gyration of the dimers are determined to be 17.0 (]SY.+-。[) 0.5 * and 16.5 (]SY.+-。[) 0.5 * for the BChl a and c, respectively. Limited observations in the very small angle region suggest that the oligomers are of considerable dimension, approximately as large as a hundred angstroms for the radius of gyration. The SANS results can be well correlated with the electronic absorption and NMR spectra and are in good agreement with other spectroscopic behavior of the small aggregates reported previously. In l997, the intact BChl c dimer structure has been further determined by high-resolution NMR.All chemial shifts of both <@D11@>D1H- and <@D113@>D1C-spectra were successfully assigned by using sarturation transfer, homo and heternuclear correlation techniques. With the formation of dimer, 3<@D11@>D1 -hydroxyl oxygen coordinates to the magnesium atom of a second BChl c molecule and the flexible peripheral substituents show dramatic conformational changes in order to reduce the steric repulsion. Extensive NOE effect was observed between several intermolecular functional groups, enablig estimation of the dimer configuration.
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