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LH2 Complex from Sulfur Bacteria Allochromatium vinosum – Natural Singlet Oxygen Sensor

Zoya K. Makhneva1, Tatyana N. Smolova1, Maksim A. Bolshakov1,a*, and Andrey A. Moskalenko1

1Institute of Basic Biological Problems, Pushchino Scientific Center for Biological Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia

* To whom correspondence should be addressed.

Received June 1, 2022; Revised August 19, 2022; Accepted August 19, 2022
It was established that in a heterogeneous model system, which consisted of two types of complexes: reaction center or core complex of photosystem 2 of higher plants and LH2 complex of the sulfur bacterium Alc. vinosum, BChl850 oxidation of the LH2 complex could be observed under illumination by the light at a wavelength of 662 nm, which is the red absorption band of Chl. It has been shown that this process induces release of singlet oxygen, which is generated in photosystem II complexes and then partially diffuses into LH2 complex, where it oxidizes BChl850. It was established by HPLC that this results in formation of a product of BChl oxidation, 3-acetylchlorophyll. The process of BChl850 oxidation is inhibited by singlet oxygen quenchers (Trolox and Na ascorbate). It is suggested that the LH2 complex from the sulfur bacterium Alc. vinosum could be used to detect generation of singlet oxygen by the chlorophyll containing samples.
KEY WORDS: photosynthetic sulfur bacteria, LH2 complex, photosystem II complexes, singlet oxygen, 662-nm light, BChl850 oxidation

DOI: 10.1134/S0006297922100091