Exciton interactions of chlorophyll tetramer in water-soluble chlorophyll-binding protein BoWSCP.

The exciton interaction of four chlorophyll a (Chl a) molecules in a symmetrical tetrameric complex of the water-soluble chlorophyll-binding protein BoWSCP was analyzed in the pH range of 3-11. Exciton splitting ΔE = 232 ± 2 cm of the Q band of Chl a into two subcomponents with relative intensities of 78.1 ± 0.

Chlorophyll a Dimers Bound in the Water-Soluble Protein BoWSCP Photosensitize the Reduction of Cytochrome c.

When bound to water-soluble proteins of the WSCP family, chlorophyll molecules form dimers structurally similar to the "special pair" of chlorophylls (bacteriochlorophylls) in photosynthetic reaction centers. Being exposed to red light (λ ≥ 650 nm) in oxygen-free solutions, chlorophyll a dimers harbored by BoWSCP holoproteins (from Brassica oleracea var. botrytis) have sensitized the reduction of cytochrome c.

[Water Soluble Chlorophyll-Binding Proteins of Plants: Structure, Properties and Functions].

Water soluble chlorophyll-binding proteins (WSCPs) of higher plants differ from most proteins containing chlorophyll orbacteriochlorophyll in that they are soluble in watr and are neither embedded in the lipid membrane nor directly involved in the process of photosynthesis. Chlorophyll molecules in WSCPs ensembles are packed in dimers within the hydrophobic zone of the protein matrix, similar to the structure of a chlorophyll "special pair" in the reaction centers of phototrophs. This fact together with the detected photosensitizing activity of WSCPs makes it possible to consider these proteins as a promising object for modelling the evolutionary prototypes of the photosynthetic apparatus, as well as for developing the artificial solar energy converters.