1995 Fiscal Year Final Research Report Summary
Isolation and Analysis of Physiological roles of thylakoid-bound NAD (P) H dehydrogenase
| Project/Area Number |
06454014
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
植物生理
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
ASADA Kozi Kyoto Univ., Res.Inst.Food Sci.Professor, 食糧科学研究所, 教授 (50027182)
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| Co-Investigator(Kenkyū-buntansha) |
MANO Junichi Kyoto Univ., Res.Inst.Food Sci.Research Associate, 食糧科学研究所, 助手 (50243100)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Synechocystis / NAD (P) H dehydrogenase / Cyclic electron flow / Cytochrome b 559 |
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| Research Abstract |
1.Measuring methods of NDH ; We have developed novel measuring methods of NDH activity using thylakoid membranes isolated from Synechocystis PCC 6803. Activity of NDH can be monitored by a) yield of chlorophyll fluorescence, b) redox change of P700, c) methylviologen-dependent Mehler reaction, d) absorbance change at 340 nm.
2.Isolation of NDH ; Two types of NDH were found by activity staining of clude extracts. A high-MW enzyme was specific to NADPH,and the other low-MW enzyme could oxidize both NADH and NADPH.The latter enzyme had 30 kDa MW and showed Km values of 12 and 47muM for NADPH and NADH,respectively. Amino acid sequence of N-terminal showed 46% homology with that of nitroreductase in Salmonella typhimurium, but no homology with that of FNR,DT diaphorase or subunits of complex I.The enzyme was inhibited by NEM,but not by rotenone, amytal, SHAM or dicumarol. These propeeties, along with high affinities with quinone alalogues, indicate that the enzyme was a novel NAD (P) H-quinone oxidoeductase.
3.Cyclic electron flow in higher plants ; We found that activity of cyclic flow could be monitored by the transient increase in chlorophyll fluorescence yield after actinic light was turned off. It was also found that cyclic electron flow in maize was mediated by cytochrome b_<559> which was sensitive to antimycin A.
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