Effect of Modification of Histidine Residues on Organization of the Pigment--Protein Complexes of Chromatium minutissimum

I. R. Prokhorenko^*, Z. K. Makhneva, and Yu. E. Erokhin

Institute of Soil Science and Photosynthesis, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia; fax: 8 (27) 79-0532; E-mail: andrei@issp.serpukhov.su

^* To whom correspondence should be addressed.

Received November 10, 1997; Revision received December 10, 1997

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The effect of diethyl pyrocarbonate on chromatophores and isolated pigment--protein complexes of Chromatium minutissimum was studied. It is shown that modification of histidine residues results in the destruction of the core antenna LHI (B880) and in a spectral shift from 850 to 830 nm in the peripheral antenna LHII (B800-850). In the purple sulfur bacterium Chromatium minutissimum the pigment--protein complexes B800-B850 (peripheral antenna, LHII) and B880 (core antenna, LHI) collect and transmit the absorbed light energy to the reaction centers. The composition of pigments and proteins as well as primary structure of the majority of polypeptides in both types of complexes from various photosynthetic bacteria have been determined.

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KEY WORDS: pigment--protein complexes, diethyl pyrocarbonate effect, photosynthetic bacteria

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