[EPR and low temperature spectrophotometric study of the phototransformation products of bacteriorhodopsin].

It is shown that BR and intermediate products of its phototransformation P600, P550 and P415 (the maximum at -196 degrees C at 419 nm) are not paramagnetic. Illumination of samples containing P415 (P419) at -- 196 degrees C with light in the region of 360-480 nm results in the formation of paramagnetic centres with a sunglet spectrum deltaH=18 Oe and g=2.002 (R1). In parallel formation of a new photoproduct P421 in the absorption spectrum is observed. During subsequent heating at -140 degrees C formation of an asymmetric signal with deltaH=45 Oe and g=2.006 and g=2.03 was observed. In the absorption spectra a dark transition. P421-P565 was observed under the same conditions. P565 differs from initial BR P570 as to its photochemical properties. R1 is identified as retinal radical, R2 as a peroxide radical of the BR-complex lipids. Paramagnetic, spectral, and photochemical properties of some products of BR transformation are compared. A scheme of oxidative-phosphorylation processes with participation of Mn ions in BR phototransformation.