[Photochromism of visual pigments. I. Formation of isochrome products during reversible transformations of frog rhodopsin].

Reversible phototransformations of rhodopsin of the frog in vitro (in digitonine extracts) at -22 degrees C under the effect of light with gamma 579 and 435 nm are reversible processes. However, while heating photogeneration product, besides true rhodopsin, thermo-unstable form is (pseudorhodopsin) is revealed. It owes its name due to the similarity of its spectral properties and photosensitivity with rhodopsin. At temperatures higher than -22 degrees C the reversibility of the system is disturbed. The nature of pseudorhodopsin is discussed.