Purification and characterization of rat liver enzyme catalyzing stereoselective reduction of acetylpyridines

Abstract

Acetylpyridines (1-3) are known as aroma components of foods, perfumes, and smoking suppressants, showing several biological activities and constituting part of the structure of some important biologically active compounds. We purified and characterized an enzyme that catalyzes the stereoselective reduction of acetylpyridines so that we could clarify its function. The enzyme participating in the reductive metabolism of 4-acetylpyridine (1) in the rat liver was purified by successively applying ammonium sulfate fractionation, anion-exchange, gel filtration, and affinity chromatography, and it was definitively identified as 3alpha-HSD. It preferentially reduced acetylpyridines (1-3) and acetophenone (7) to their corresponding (S)-alcohols, with high enantioselectivity. Kinetic analyses of the compounds were performed, and the V(max)/K(m) values decreased in the order of 4-, 2-, and 3-acetylpyridine (1, 3, 2), while acetophenone (7) showed almost the same value as 3-acetylpyridine (2). These results suggested that the reduction of the substrates by 3alpha-HSD is affected by the nitrogen atom in the aromatic ring.

Asymmetric Reduction of Heteroaryl Methyl Ketones Using <i>Daucus carota</i>

“…[20,21]. When compared to earlier reports [22][23][24][25], the present study demonstrates that the dehydrogenase enzymes present in D.carota has reduced keto groups attached to five member heteroaryl compounds (1h -1j) (pyrrole, furan and thiophene) with good enantio-selectivity. thus demonstrating the broad specificity of the dehydrogenase enzyme present in the carrot.…”

Recent progress in biocatalysis for asymmetric oxidation and reduction

“…For example, the enzyme that reduces acetylpyridine to the corresponding (S)-alcohols isolated from rat liver was found to be the rat liver 3a-hydoxysteroid dehydrogenase (3a-HSD) from amino acid sequences. 76,77 The natural substrate of 3a-HSD is steroids and is known to catalyze the conversion of androsterone and naloxone. 78 Moreover, the kinetics of 3a-HSD was fully investigated with extraneous substrates, which gives the information useful for drug design to exploit this reduction pathway.…”

Biotransformation of organic compounds in vivo using larvae of beetles (Allomyrina dichotoma) as biocatalysts

“…In the reductions of the acetyl group, the enzymatic affinity for each isomer was very different. The enantioselectivity for the reduction was the highest for α-acetylpyridine (18a), followed in order by β-acetylpyridine (18b) and γ-acetylpyridine (18c) to give α-, β-, and γ-pyridylethanols (19a, b, c) in 15% (60% ee), 12% (18%ee), and 5% (racemic) yields, respectively (Takeshita et al, 1987;Takeshita and Yoshida, 1990;Uwai et al, 2005) (Scheme 4). The stereoselectivities of the reduction of these acetylpyridine derivatives differed form reported data obtained using baker's yeast (Takeshita et al, 1987) and rat liver S-9 fraction (Uwai et al, 2005).…”