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Two acidic and three basic forms of monomeric dihydrodiol dehydrogenase with molecular weights in the range of 36,000-39,000 were purified from human liver. One acidic enzyme (pI 5.2), which was specific for NADP- and dihydrodiols of benzene and naphthalene, was immunologically identified as aldehyde reductase. The other four enzymes oxidized alicyclic alcohols as well as the dihydrodiols using both NADP+ and NAD+ as cofactors, but showed differences in specificity for hydroxysteroids and inhibitor sensitivity. Two of the basic enzymes (pI 9.7 and 9.1) exhibited a 20 alpha-hydroxysteroid dehydrogenase activity and sensitivity to 1,10-phenanthroline, whereas the third basic enzyme (pI 7.6) oxidized some 3 alpha-hydroxysteroids at low rates and was inhibited by cyclopentane-1,1-diacetic acid. Another acidic enzyme, which accounted for the largest amount of enzyme activity in the tissue and appeared in two heterogenous forms with pI values of 5.9 and 5.4, showed a high 3 alpha-hydroxysteroid dehydrogenase activity and was the most sensitive to inhibition by medroxyprogesterone acetate. The Km values of the enzymes, except the pI 5.2 enzyme, for hydroxysteroids (10(-6) to 10(-7) M) were lower than those for xenobiotic alcohols.

Two monomeric dihydrodiol dehydrogenases with pI values of 5.4 and 7.6 were co-purified with androsterone dehydrogenase activity to homogeneity from human liver. The two enzymes differed from each other on peptide mapping and in their heat-stabilities; with respect to the latter the dihydrodiol dehydrogenase and 3 alpha-hydroxysteroid dehydrogenase activities of the respective enzymes were similarly inactivated. The pI 5.4 enzyme was equally active towards trans- and cis-benzene dihydrodiols, and towards (S)- and (R)-forms of indan-1-ol and 1,2,3,4-tetrahydronaphth-1-ol and oxidized the 3 alpha-hydroxy group of C19-, C21- and C24-steroids, whereas the pI 7.6 enzyme showed high specificity for trans-benzene dihydrodiol, (S)-forms of the alicyclic alcohols and C19- and C21-steroids. Although the two enzymes reduced various xenobiotic carbonyl compounds and the 3-oxo group of C19- and C21-steroids, and were A-specific in the hydrogen transfer from NADPH, only the pI 5.4 enzyme showed reductase activity towards 7 alpha-hydroxy-5 beta-cholestan-3-one and dehydrolithocholic acid. The affinity of the two enzymes for the steroidal substrates was higher than that for the xenobiotic substrates. The two enzymes also showed different susceptibilities to the inhibition by anti-inflammatory drugs and bile acids. Whereas the pI-5.4 enzyme was highly sensitive to anti-inflammatory steroids, showing mixed-type inhibitions with respect to indan-1-ol and androsterone, the pI 7.6 enzyme was inhibited more potently by non-steroidal anti-inflammatory drugs and bile acids than by the steroidal drugs, and the inhibitions were all competitive. These structural and functional differences suggest that the two enzymes are 3 alpha-hydroxysteroid dehydrogenase isoenzymes.

The synthesis of poly(VDF-ter-TFMA-ter-HFP) terpolymers (where VDF, TFMA, and HFP stand for vinylidene fluoride, R-trifluoromethacrylic acid, and hexafluoropropylene, respectively) and their blends with silica filler for preparing original fluorocomposites are presented. First, the radical terpolymerization of VDF, TFMA, and HFP by iodine transfer polymerization without any surfactant was investigated in the presence of 1,6-diiodoperfluorohexane as the chain transfer agent. TFMA monomer was well incorporated, and the terpolymers were obtained in good yields (>65%). The microstructures of the produced terpolymers were characterized by 1 H and 19 F NMR spectroscopy to assess the amounts of each comonomer, the molecular weights, and the nature of the end groups of the copolymers. Molar percentages of VDF, TFMA, and HFP were in the 45-80, 12-53, and 1-8 ranges, respectively, whereas the molecular weights of the resulting terpolymers were ca. 5400-12 600 g 3 mol -1 . End groups were VDF-I only with a high amount of CH 2 CF 2 -I. Then, these poly(VDF-ter-TFMA-ter-HFP) terpolymers were involved in the preparation of the fluorinated polymers/silica nanocomposites by sol-gel reactions in the presence of tetraethoxysilane and silica nanoparticles under alkaline and acidic conditions, respectively. Interestingly, poly(VDF-ter-TFMA-ter-HFP) terpolymer/silica nanocomposites, which were prepared under alkaline conditions, showed exceptional thermal properties because they were found to exhibit almost no weight loss up to 800 °C.

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