ISSN:
1573-5079
Keywords:
energy transfer
;
temperature dependence
;
Rhodobacter sphaeroides
;
Rhodospirillum rubrum
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Decay of the bacteriochlorophyll excited state was measured in membranes of the purple bacteria Rhodospirillum (R.) rubrum, Rhodobacter (Rb.) sphaeroides wild type and Rb. sphaeroides mutant M21 using low intensity picosecond absorption spectroscopy. The excitation and probing pulses were chosen in the far red wing of the long wavelength absorption band, such that predominantly the minor antenna species B896 was excited. The decay of B896 was studied between 77 and 177K under conditions that the traps were active. In all species the B896 excited state decay is almost temperature independent between 100 and 177K, and probably between 100 and 300 K. In this temperature range the decay rates for the various species are very similar and close to 40 ps. Below 100 K this rate remains temperature independent in Rb. sphaeroides w. t. and M21, while in R. rubrum a steep decrease sets in. An analysis of this data with the theory of nuclear tunneling indicates an activation energy for the final transfer step from B896 to the special pair of 70cm-1 for R. rubrum and 30cm-1 or less for Rb. sphaeroides.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00048300
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