Table II.

Mitochondrial metabolism of α-KIC and IV-CoA

SubstrateIncubation DurationAcid-Stable MetabolitesMG-CoAHMG-CoA
min dpm (×103)/mg protein %
IV-CoA147.8  (+10.3)ND1-a ND
580.3  (+17.3)64.6  (+13.9)NDNDNDND
20106.2  (+22.8)64.9  (+13.9)NDND100ND
60166.4  (+35.8)77.2  (+16.6)17ND83ND
α-KIC149.9  (+10.7)NDND
563.7  (+13.7)64.5  (+13.9)NDNDNDND
2088.5  (+19.0)67.1  (+14.4)NDND100ND
60146.3  (+31.4)100.8  (+21.5)NDND100ND

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).

    • F1-a ND, Not detected.