Spectroscopic characterization of reaction centers of the (M) Y210W mutant of the photosynthetic bacterium Rhodobacter sphaeroides

Spectroscopic characterization of reaction centers of the (M) Y210W mutant of the photosynthetic bacterium Rhodobacter sphaeroides

The tyrosine-(M)210 of the reaction center of Rhodobacter sphaeroides 2.4.1 has been changed to a tryptophan using site-directed mutagenesis. The reaction center of this mutant has been characterized by low-temperature absorption and fluorescence spectroscopy, time-resolved sub-picosecond spectrosco...

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Bibliographic Details
Published in:Photosynthesis research Vol. 40; no. 1; pp. 55 - 66
Main Authors: SHOCHAT, S, ARLT, T, HOFF, A. J, FRANCKE, C, GAST, P, VAN NOORT, P. I, OTTE, S. C. M, SCHELVIS, H. P. M, VIJGENBOOM, E, VRIEZE, J, ZINTH, W
Format: Journal Article
Language:English
Published: Dordrecht Kluwer 01-04-1994
Subjects:
Bacteriology
Biological and medical sciences
Fundamental and applied biological sciences. Psychology
Metabolism. Enzymes
Microbiology
Temperature
Reaction center
Growth
Charge separation
Fluorescence
Electron transfer
Rhodospirillaceae
Cofactor
Rhodospirillales
Absorption
Bacteriochlorophyll
Investigation method
Rhodobacter sphaeroides
Light
Bacteria
Rhodospirillineae
Light effect
Radiolabelling
Primary electron donor
Polypeptide
Aminoacid
Dimer
Mutation
Photosynthesis
Physicochemical properties
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Summary:The tyrosine-(M)210 of the reaction center of Rhodobacter sphaeroides 2.4.1 has been changed to a tryptophan using site-directed mutagenesis. The reaction center of this mutant has been characterized by low-temperature absorption and fluorescence spectroscopy, time-resolved sub-picosecond spectroscopy, and magnetic resonance spectroscopy. The charge separation process showed bi-exponential kinetics at room temperature, with a main time constant of 36 ps and an additional fast time constant of 5.1 ps. Temperature dependent fluorescence measurements predict that the lifetime of P(*) becomes 4-5 times slower at cryogenic temperatures. From EPR and absorbance-detected magnetic resonance (ADMR, LD-ADMR) we conclude that the dimeric structure of P is not significantly changed upon mutation. In contrast, the interaction of the accessory bacteriochlorophyll BA with its environment appears to be altered, possibly because of a change in its position.
ISSN:0166-8595
1573-5079
DOI:10.1007/BF00019045