Biochemical aspects of the visual process. XIX. Formation of isorhodopsin from photolyzed rhodopsin by bacterial action

A washed and concentrated suspension of bacteria (e.g. Proteus mirabilis) causes a rapid and almost complete conversion of photolyzed rhodopsin to isorhodopsin. Upon ultrasonication of the bacteria the activity is retained in the supernatant. The isorhodopsin formation is very sensitive to oxygen. This suggests that an easily oxidized bacterial product is able to isomerize in darkness all-trans-retinaldehyde present in a photolyzed rhodopsin preparation to the 9-cis-isomer.