How the Protein Environment Can Tune the Energy, the Coupling, and the Ultrafast Dynamics of Interacting Chlorophylls: The Example of the Water-Soluble Chlorophyll Protein

Abstract An investigation of the photoexcited triplet state of chlorophyll (Chl) a in the water-soluble chlorophyll protein (WSCP) of Brassica oleracea has been carried out by means of electron-nuclear double resonance (ENDOR), achieving a complete assignment of the observed hyperfine couplings corresponding to methine protons and methyl groups of Chl a triplet state. The triplet-state properties, and in particular the hyperfine couplings, were found to be similar to those previously reported for Chl a in the WSCP of Lepidium virginicum. Therefore, the porphyrin ring deformation observed in Brassica oleracea WSCP seems to only slightly affect the spin density of 3Chl a. This may be relevant when considering the robustness of triplet–triplet energy transfer mechanisms, relying on wavefunction overlap, in systems, such as the photosynthetic light-harvesting complexes, in which Chl triplet states with distorted geometries are involved.

Download Full-text

Isolation of water-soluble chlorophyll protein from the leaves of Chenopodium album

Biochimica et Biophysica Acta ◽

10.1016/0006-3002(63)90615-2 ◽

1963 ◽

Vol 75 ◽

pp. 293-298 ◽

Cited By ~ 40

Author(s):

Eijiro Yakushiji ◽

Keigo Uchino ◽

Yasutomo Sugimura ◽

Irie Shiratori ◽

Fusako Takamiya

Keyword(s):

Chenopodium Album ◽

Water Soluble ◽

Chlorophyll Protein

Download Full-text

How water-mediated hydrogen bonds affect chlorophyll a/b selectivity in Water-Soluble Chlorophyll Protein

Scientific Reports ◽

10.1038/s41598-019-54520-4 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 7

Author(s):

Alessandro Agostini ◽

Elena Meneghin ◽

Lucas Gewehr ◽

Danilo Pedron ◽

Daniel M. Palm ◽

...

Keyword(s):

Hydrogen Bond ◽

Binding Sites ◽

Photophysical Properties ◽

Water Soluble ◽

Variable Degree ◽

Formyl Group ◽

Hydrogen Bond Networks ◽

Conformational Freedom ◽

Chlorophyll Protein ◽

Hydrogen Bonded

AbstractThe Water-Soluble Chlorophyll Protein (WSCP) of Brassicaceae is a remarkably stable tetrapyrrole-binding protein that, by virtue of its simple design, is an exceptional model to investigate the interactions taking place between pigments and their protein scaffold and how they affect the photophysical properties and the functionality of the complexes. We investigated variants of WSCP from Lepidium virginicum (Lv) and Brassica oleracea (Bo), reconstituted with Chlorophyll (Chl) b, to determine the mechanisms by which the different Chl binding sites control their Chl a/b specificities. A combined Raman and crystallographic investigation has been employed, aimed to characterize in detail the hydrogen-bond network involving the formyl group of Chl b. The study revealed a variable degree of conformational freedom of the hydrogen bond networks among the WSCP variants, and an unexpected mixed presence of hydrogen-bonded and not hydrogen-bonded Chls b in the case of the L91P mutant of Lv WSCP. These findings helped to refine the description of the mechanisms underlying the different Chl a/b specificities of WSCP versions, highlighting the importance of the structural rigidity of the Chl binding site in the vicinity of the Chl b formyl group in granting a strong selectivity to binding sites.

Download Full-text