Table II.
Mitochondrial metabolism of α-KIC and IV-CoA
| Substrate | Incubation Duration | Acid-Stable
Metabolites
|
MG-CoA
|
HMG-CoA
|
|||
|---|---|---|---|---|---|---|---|
| −Avidin | +Avidin | −Avidin | +Avidin | −Avidin | +Avidin | ||
| min | dpm (×103)/mg protein | % | |||||
| IV-CoA | 1 | 47.8 (+10.3) | – | NDa | – | ND | – |
| 5 | 80.3 (+17.3) | 64.6 (+13.9) | ND | ND | ND | ND | |
| 20 | 106.2 (+22.8) | 64.9 (+13.9) | ND | ND | 100 | ND | |
| 60 | 166.4 (+35.8) | 77.2 (+16.6) | 17 | ND | 83 | ND | |
| α-KIC | 1 | 49.9 (+10.7) | – | ND | – | ND | – |
| 5 | 63.7 (+13.7) | 64.5 (+13.9) | ND | ND | ND | ND | |
| 20 | 88.5 (+19.0) | 67.1 (+14.4) | ND | ND | 100 | ND | |
| 60 | 146.3 (+31.4) | 100.8 (+21.5) | ND | ND | 100 | ND | |
Mitochondrial extracts were incubated with α-KIC or IV-CoA, and their conversion to MC-CoA was monitored by the MCCase-catalyzed (avidin-sensitive) incorporation of radioactivity from NaH14CO3 into acid-stable products, which were identified as [14C]MG-CoA or [14C]HMG-CoA by HPLC analysis. The amount of radioactivity present in each metabolite is expressed as a percentage of the total radioactivity recovered during HPLC fractionation, discounting the residual [14C]bicarbonate peak. For acid-stable metabolites, the variance was dependent on the mean and a log transformation was used. Consequently, 1 se above the mean (shown) was greater than 1 se below the mean (not shown).
a
ND, Not detected.