Catalyzes the reduction of a wide range of aldehydes including aliphatic fatty aldehydes (C4-C16), into their corresponding alcohols. Has a strong preference for NADPH over NADH as the electron donor. Cannot use glyceraldehyde or a ketone as substrate. Is a relevant source of NADPH-dependent aldehyde reductase activity in E.coli. The in vivo functions of Ahr has yet to be determined. a primary alcohol + NADP(+) = an aldehyde + H(+) + NADPH Binds 2 Zn(2+) ions per subunit. kcat is 333 sec(-1) for acetaldehyde reduction. kcat is 207 sec(-1) for propionaldehyde reduction. kcat is 464 sec(-1) for butyraldehyde reduction. kcat is 51 sec(-1) for isobutyraldehyde reduction. kcat is 78 sec(-1) for crotonaldehyde reduction. kcat is 312 sec(-1) for glutaraldehyde reduction. kcat is 2.6 sec(-1) for 5-hydroxyvalerate reduction. kcat is 419 sec(-1) for hexanaldehyde reduction. kcat is 313 sec(-1) for benzaldehyde reduction. kcat is 224 sec(-1) for furfural reduction. kcat is 13.8 sec(-1) for butanol oxidation. kcat is 12.9 sec(-1) for 1,4-butanediol oxidation. Optimum temperature is 37-50 degrees Celsius using butyraldehyde as substrate. This enzyme can be applied to the microbial production of fatty alcohols that have numerous applications as fuels, fragrances, emollients, food additives, and detergents. Thus, together with complementing enzymes, the broad substrate specificity of Ahr opens the road for direct and tailored enzyme-catalyzed conversion of lipids into user-ready chemical commodities. Belongs to the zinc-containing alcohol dehydrogenase family. Extended N-terminus.