Journal
JOURNAL OF PHYSICAL CHEMISTRY B
Volume 120, Issue 40, Pages 10483-10495Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.jpcb.6b07803
Keywords
-
Categories
Funding
- National Science Foundation [MCB-0417142]
Ask authors/readers for more resources
We explored the rich satellite hole structures emerging as a result of spectral hole burning in cyanobacterial photosystem I (PSI) and demonstrated that hole burning properties of PSI, particularly at high resolution, are strongly affected by the oxidation state of the primary donor P700, as P700(+) effectively quenches the excitations of the lowest-energy antenna states responsible for fluorescence. Obtaining better control of this variable will be crucial for high-resolution ensemble experiments on protein energy landscapes in PSI. The separate nonphotochemical spectral hole burning (NPHB) signatures of various red antenna states were obtained, allowing for additional constraints on excitonic structure based calculations. Preliminary evidence is presented for an additional red state of PSI of T. elongatus peaked at 712.6 nm, distinct from previously reported C708 and C715 states and possibly involving chlorophyll B15. Excitation at wavelengths as long as 800 rim results in charge separation at cryogenic temperatures in PSI also in Synechacystis sp. PCC 6803. Both the P700(+) minus P700 holes and nonphotochemical spectral holes were subjected to thermocycling. The distribution-of barriers manifesting in recovery of the P700(+) minus P700 signature contains two components in sample-dependent proportions, likely reflecting the percentages Of FA and F-B clusters being successfully prereduced before the optical experiment. The barrier distribution for the recovery of the lower-energy nonphotochemical spectral holes resembles those observed for other pigment protein complexes, suggesting similar structural elements are responsible for NPHB. Higher-energy components exhibit evidence of domino effects such as shifts of certain bands persisting past the lower-energy hole recovery. Thus, conformational changes triggered by excitation of one pigment likely can affect multiple pigments in this tightly packed-system.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available