. directions with any retinol/retinalpair, except ADH4 with 11-cis-retinoids. Interestingly, thetwo ADH4 enzymes showed an 8-fold higher kcat/Kmvalue with 11-cis-retinol than with 11-cis-retinal. 7.5,than the human enzyme [31,42].Kinetic constants with retinoidsKinetic constants with all-trans-retinol and all-trans-ret-inal, and with the cis-isomers of retinol and retinal (7-cis-,9-cis-,. constants with ethanol and hexanol, for therecombinant ADH1 and ADH4, were determined at pH 7.5and 10.5 (Table 1). For both enzymes, the Kmvalues with hexanol were much lower than those with ethanol,...