Inhibition by acetyl-CoA of hepatic carnitine acyltransferase and fatty acid oxidation.
نویسندگان
چکیده
At micromolar concentrations, acetyl-CoA inhibited hepatic carnitine acyltransferase activity and mitochondrial fatty acid oxidation. The inhibitory effects were not nearly as potent on a molar basis as those of malonyl-CoA; nevertheless, the cytosolic concentrations of acetyl-CoA, as yet unknown, may be sufficient (greater than 30 microM) to curtail appreciably the mitochondrial transfer of long-chain acyl-CoA units and fatty acid oxidation. Hence acetyl-CoA may also partially regulate hepatic ketogenesis.
منابع مشابه
In support of the roles of malonyl-CoA and carnitine acyltransferase I in the regulation of hepatic fatty acid oxidation and ketogenesis.
The rate of fatty acid synthesis in hepatocytes from meal-fed rats was manipulated over a wide range using glucose, lactate, and pyruvate to drive the system maximally, and glucagon, 5-(tetradecyloxy)-2-furoic acid (RMI 14,514), or a combination of both agents to inhibit lipogenesis. Measurements were made of cellular malonyl-CoA levels, long chain acylcarnitine concentration, and [l-‘4C]oleate...
متن کاملImportance of experimental conditions in evaluating the malonyl-CoA sensitivity of liver carnitine acyltransferase. Studies with fed and starved rats.
The experiments reconfirm the powerful inhibitory effect of malonyl-CoA on carnitine acyltransferase I and fatty acid oxidation in rat liver mitochondria (Ki 1.5 microM). Sensitivity decreased with starvation (Ki after 18 h starvation 3.0 microM, and after 42 h 5.0 microM). Observations by Cook, Otto & Cornell [Biochem. J. (1980) 192, 955--958] and Ontko & Johns [Biochem. J. (1980) 192, 959--96...
متن کاملEffect of pH on malonyl-CoA inhibition of carnitine palmitoyltransferase I.
Malonyl-CoA inhibition of carnitine palmitoyltransferase I was found to be very pH-dependent. Malonyl-CoA concentrations causing 50% inhibition (I50) at pH 6.0, 6.5, 7.0, 7.5 and 8.0 were 0.04, 1, 9, 40 and 200 microM respectively. It is suggested that a lowering of intracellular pH, such as might occur in ketoacidosis, may attenuate hepatic fatty acid oxidation by increasing malonyl-CoA sensit...
متن کاملA possible role for malonyl-CoA in the regulation of hepatic fatty acid oxidation and ketogenesis.
Studied on the oxidation of oleic and octanoic acids to ketone bodies were carried out in homogenates and in mitochondrial fractions of livers taken from fed and fasted rats. Malonyl-CoA inhibited ketogenesis from the former but not from the latter substrate. The site of inhibition appeared to be the carnitine acyltransferase I reaction. The effect was specific and easily reversible. Inhibitory...
متن کاملEffects of starvation on the carnitine palmitoyltransferase of hepatic peroxisomes.
I t is generally accepted that the mitochondria1 carnitine palmitoyltransferases play an important role in the regulation of hepatic fatty acid oxidation [ I ] . These two enzymes express their activities on either side of the mitochondrial inner membrane that acts as a barrier to the transfer of fatty acids into the mitochondrial matrix. The enzyme that lies outsidc this barrier is located on ...
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ورودعنوان ژورنال:
- The Biochemical journal
دوره 216 2 شماره
صفحات -
تاریخ انتشار 1983