RETINOID METABOLISM AND CONVERSION OF RETINOL TO DEHYDRORETINOL IN THE CRAYFISH (PROCAMBARUS CLARKII) RETINA

Activities of retinylester hydrolase (REHase) and retinol dehydrogenase (RDHase) were detected in the crayfish retina which has two visual pigment chromophores and three stored retinoids.RDHase and 11-cis REHase activities were localized to rhabdomal fraction and enzymes were specific to 11-cis isomers of substrates. Overall reaction from retinylester to retinal was highly specific to 11-cis isomers and this reaction was not selective between retinol and dehydroretinol.When 11-cis [³H]-retinol was incubated with retina homogenates, radioactivity was detected in 11-cis dehydroretinol.These results suggest that retinol is converted to dehydroretinol after hydrolysis of retinylesters.