How fine-tuned for energy transfer is the environmental noise produced by proteins around biological chromophores?

2018 ◽  
Vol 20 (25) ◽  
pp. 17279-17288 ◽  
Author(s):  
Kirsten Claridge ◽  
Daniele Padula ◽  
Alessandro Troisi
Keyword(s):  
Energy Transfer ◽  
Protein Complexes ◽  
Local Environment ◽  
Environmental Noise ◽  
Biological Functions ◽  
Significant Difference ◽  
Pigment Protein Complexes

Analysis of intermolecular motions of pigment–protein complexes shows no significant difference in influence of local environment despite different biological functions.

scholarly journals A photosynthetic antenna complex foregoes unity carotenoid-to-bacteriochlorophyll energy transfer efficiency to ensure photoprotection

2020 ◽  
Vol 117 (12) ◽  
pp. 6502-6508 ◽  
Author(s):  
Dariusz M. Niedzwiedzki ◽  
David J. K. Swainsbury ◽  
Daniel P. Canniffe ◽  
C. Neil Hunter ◽  
Andrew Hitchcock
Keyword(s):  
Energy Transfer ◽  
Transient Absorption ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Fluorescence Emission ◽  
Energy Transfer Efficiency ◽  
Transfer Efficiency ◽  
Light Harvesting Complexes ◽  
Antenna Complex ◽  
Pigment Protein Complexes

Carotenoids play a number of important roles in photosynthesis, primarily providing light-harvesting and photoprotective energy dissipation functions within pigment–protein complexes. The carbon–carbon double bond (C=C) conjugation length of carotenoids (N), generally between 9 and 15, determines the carotenoid-to-(bacterio)chlorophyll [(B)Chl] energy transfer efficiency. Here we purified and spectroscopically characterized light-harvesting complex 2 (LH2) fromRhodobacter sphaeroidescontaining theN= 7 carotenoid zeta (ζ)-carotene, not previously incorporated within a natural antenna complex. Transient absorption and time-resolved fluorescence show that, relative to the lifetime of the S1state of ζ-carotene in solvent, the lifetime decreases ∼250-fold when ζ-carotene is incorporated within LH2, due to transfer of excitation energy to the B800 and B850 BChlsa. These measurements show that energy transfer proceeds with an efficiency of ∼100%, primarily via the S1→ Qxroute because the S1→ S0fluorescence emission of ζ-carotene overlaps almost perfectly with the Qxabsorption band of the BChls. However, transient absorption measurements performed on microsecond timescales reveal that, unlike the nativeN≥ 9 carotenoids normally utilized in light-harvesting complexes, ζ-carotene does not quench excited triplet states of BChla, likely due to elevation of the ζ-carotene triplet energy state above that of BChla. These findings provide insights into the coevolution of photosynthetic pigments and pigment–protein complexes. We propose that theN≥ 9 carotenoids found in light-harvesting antenna complexes represent a vital compromise that retains an acceptable level of energy transfer from carotenoids to (B)Chls while allowing acquisition of a new, essential function, namely, photoprotective quenching of harmful (B)Chl triplets.

scholarly journals The effects of Triton X-100 and n-octyl β-d-glucopyranoside on energy transfer in photosynthetic membranes

1984 ◽  
Vol 224 (3) ◽  
pp. 989-993 ◽  
Author(s):  
D J Murphy ◽  
I E Woodrow
Keyword(s):  
Energy Transfer ◽  
Protein Complexes ◽  
Fluorescence Emission ◽  
Emission Peak ◽  
Wavelength Shift ◽  
Emission Characteristics ◽  
Ionic Detergents ◽  
Reversible Dissociation ◽  
Pigment Protein Complexes ◽  
Triton X

The effects of the non-ionic detergents Triton X-100 and n-octyl beta-D-glucopyranoside on energy transfer between pigment-protein complexes of Pisum sativum thylakoids were investigated. This was done by monitoring the 77K fluorescence-emission characteristics of stacked and unstacked thylakoids exposed to a range of detergent concentrations. At sub-critical micellar concentrations, the detergents had little effect, whereas above these concentrations they caused increases of up to 20-fold in short-wavelength fluorescence intensity and a shift in its maximum wavelength from 685 to 680 nm. Fluorescence-emission intensities at 695 and 735 nm were relatively unaffected by detergent treatments, although Triton X-100 caused a wavelength shift in the emission peak from 735 to 728 nm. The results are discussed in terms of reversible dissociation of pigment-protein complexes induced by mild detergent solubilization and the consequent cessation of inter-complex energy transfer.

Chlorophyll Photobleaching in Pigment-Protein Complexes

1986 ◽  
Vol 41 (3) ◽  
pp. 284-290 ◽  
Author(s):  
Robert Carpentier ◽  
Roger M. Leblanc ◽  
Guy Bellemare
Keyword(s):  
Energy Transfer ◽  
Hordeum Vulgare ◽  
Chlamydomonas Reinhardtii ◽  
Protein Complexes ◽  
Thylakoid Membranes ◽  
Wild Type ◽  
Protection Mechanism ◽  
Long Wavelength ◽  
Pigment Protein Complexes ◽  
Type Mutant

Pigment photobleaching was performed in thylakoid membranes of Hordeum vulgare (wild type, mutant Chlorina f2, Norfluranzon treated seedlings) and in pigment-protein complexes (CP-I and LHCP) isolated from H. vulgare and Chlamydomonas reinhardtii. Multiphasic kinetics were obtained in all of the above cases. Energy transfer towards pigments absorbing at longer wavelength is postulated as a general protection mechanism against photobleaching. This mechanism explains a substantial bleaching of carotenoids and a faster bleaching of chlorophyll aggregates, absorbing at long wavelength. These conclusions were valid for isolated complexes as well as for thylakoid membranes, although membranes were less sensitive to light.

scholarly journals Excitation energy transfer between monomolecular layers of light harvesting LH2 and LH1-reaction centre complexes printed on a glass substrate

Lab on a Chip ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 2529-2538
Author(s):  
Xia Huang ◽  
Cvetelin Vasilev ◽  
C. Neil Hunter
Keyword(s):  
Energy Transfer ◽  
Glass Substrate ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Excitation Energy Transfer ◽  
Artificial Light ◽  
Reaction Centre ◽  
Bacterial Pigment ◽  
Pigment Protein Complexes ◽  
Monomolecular Layers

Remarkably stable artificial light-harvesting arrays capable of harvesting and trapping solar energy were fabricated using purified bacterial pigment–protein complexes.

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