Apparent Michaelis-Menten constants (Km) and apparent Vmax of lovastatin metabolite formation by human and pig liver and small intestinal microsomes
| Microsomal Preparation | 6′β-Hydroxylovastatin | 6′-Exomethylene Lovastatin | 3"-Hydroxylovastatin |
|---|---|---|---|
| μM | |||
| Apparent K m | |||
| Human liver | 7.9 ± 3.2 | 8.1 ± 3.5 | N.D. |
| (5.2–12.0) | (4.1–11.4) | ||
| Human small intestine | 11.2 ± 3.3 | 22.2 ± 9.0 | N.D. |
| (8.2–14.3) | (12.1–33.8) | ||
| Pig liver | 31.7 ± 14.5 | 82.9 ± 32.4 | N.D. |
| (18.6–52.4) | (62.9–131.0) | ||
| Pig small intestine | 34.2 ± 9.7 | 80.7 ± 42.3 | 53.9 ± 20.3 |
| (19.9–41.1) | (44.1–140.6) | (37.6–81.7) | |
| pmol · min−1 · mg−1 protein | |||
| ApparentV max | |||
| Human liver (range) | 1576 ± 778 | 1128 ± 531 | N.D. |
| (897–2688) | (587–1859) | ||
| Human small intestine (range) | 155.4 ± 28.6 | 69.8 ± 13.5 | N.D. |
| (114–176) | (52–84) | ||
| Pig liver (range) | 152.6 ± 66.1 | 82.8 ± 32.4 | N.D. |
| (90–246) | (40–143) | ||
| Pig small intestine (range) | 68.3 ± 34.6 | 33.9 ± 19.2 | 49.0 ± 48.5 |
| (45–120) | (22–59) | (14–119) | |
All values are mean ± S.D. (n = 4 preparations from different individuals). Apparent Km andVmax values were calculated after linearization according to Hanes-Woolf and data fitting (SigmaPlot software, Version 4.0). Representative Hanes-Woolf plots are shown in Fig. 2. Ranges are shown in parentheses.
N.D., not detectable.