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  • Title: On the capacity of the beta-oxidation of palmitate and palmitoyl-esters in rat liver mitochondria.
    Author: Farstad M, Berge R.
    Journal: Acta Physiol Scand; 1978 Nov; 104(3):337-48. PubMed ID: 31061.
    Abstract:
    The beta-oxidation of palmitate, palmitoyl-CoA and palmitoyl-L-carnitine proceeded at a high rate in isolated rat liver mitochondria. At high concentrations (100 nmol/mg protein) the oxidation of palmitate and palmitoyl-CoA was only partly carnitine dependent. All substrates were most rapidly oxidized in the presence of oxaloacetate and state 3 conditions. Succinate inhibited beta-oxidation especially in state 4 conditions. beta-Oxidation was faster in hypotonic than in isotonic medium both in state 3 and state 4 conditions. Hypertonicity inhibited beta-oxidation. The initial formation of palmitoyl-CoA from palmitate, CoA and ATP was faster than the oxidation of palmitate under identical conditions. The presence of bovine serum albumin inhibited the beta-oxidation, especially with palmitoyl-CoA or free palmitate as the substrates. Mitochondria contain a palmitoyl-CoA hydrolase which may influence the available intramitochondrial palmitoyl-CoA. The present results demonstrate no single rate limiting step in the beta-oxidation in vitro. Both the NADH/NAD ratio, competition for the respiratory chain, the level of ADP, binding of palmitoyl-CoA to extramitochondrial protein, and possibly intramitochondrial hydrolysis of palmitoyl-CoA all seem to influence the rate of beta-oxidation in vitro. It is suggested that in vivo the most important factor is the availability of acyl-CoA to the outer carnitine palmitoyl-transferase of the mitochondria.
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