Characteristics of the photoconversion of rhodopsin in the early stages of photolysis.

Low-temperature spectrophotometry was used to study the primary stages of rhodopsin photolysis. A digitonin extract of rhodopsin was irradiated at -155 degrees C with blue light of wavelength 436 nm. The stage of the bathorhodopsin --> lumirhodopsin conversion was accompanied by the simultaneous formation of several products. Formation of an intermediate product spectrally similar to the known "blue-shifted intermediate" (BSI) was demonstrated. It is suggested that the appearance of more than one intermediate product at each stage of photolysis reflects the existence of several conformational states of the rhodopsin molecule during its photoconversion.