It was shown the 9-cis-13-demetilretinal incorporation into bacterioop
sin with formation of the covalent purple complex. This result was pre
dicted by our hypothesis about structure of the BR chromophore cavity
(Mel. Biol. (Moscow) 1995. V. 29. P. 1398-1407), confirms a hypothesis
and removes main objection, known on a literary data.