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

Abstract

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. There are two classes of proteins in the WSCP family, class I and class II the representatives of these classes have a weak degree of homology in the primary structure, but a high degree of similarity in the tertiary and quaternary structure. One of the features of class I WSCPs is photoconversion, that is, to change the structure and spectral properties of the chromophore under the action of light. The functions of WSCPs in the plant are thought to be associated with stress protection.

Keywords: Kunitz-type protease inhibitors; absorption spectroscopy; chlorophyll dimers; circle dichroism; evolution of the photosynthetic apparatus; fluorescence spectroscopy; reaction center; secondary structure; tertiary structure; water soluble chlorophyll-binding proteins.