Figure 6.

Separation of radioactive metabolites by HPLC. Representative chromatograms depicting metabolites arising from the catabolism of MC-CoA by mitochondrial extracts in the presence of NaH¹⁴CO₃ and cofactors after 5-min (A) or 45-min (B) incubations. After 5 min [¹⁴C]MG-CoA and [¹⁴C]HMG-CoA were at similar levels and [¹⁴C]acetoacetate was barely detectable. After 45 min [¹⁴C]HMG-CoA had exceeded [¹⁴C]MG-CoA and [¹⁴C]acetoacetate had increased. Representative chromatograms depicting metabolites arising from the catabolism of [U-¹⁴C]Leu by mitochondrial extracts in the presence of 10 μg of avidin after a 2-h (C) or 6-h (D) incubation. After 2 h α-[¹⁴C]-KIC accumulated to a substantial level and [¹⁴C]IV-CoA accumulation was in progress. After 6 h the level of α-[¹⁴C]-KIC diminished, indicating that the rate of its disappearance had exceeded its formation. [¹⁴C]IV-CoA continued to accumulate and [¹⁴C]MC-CoA appeared. [¹⁴C]Isovaleric acid was likely a decarboxylation product of α-[¹⁴C]-KIC, possibly arising nonenzymatically.