Acetyl-CoA production

Ketogenesis (Figure 6.19) occurs in the liver at most times but is greatly accelerated when acetyl-CoA production from p-oxidation of fatty acids exceeds the capacity of the TCA cycle to form citrate, that is during periods of starvation or in diabetics who have... 

Two-carbon donor/product Malonyl CoA donor of one acetyl group Acetyl CoA product of 1 P-oxidation... 

Occurs in liver when acetyl CoA production exceeds the limits of its oxidation in the citric acid cycle---------------> starvation or uncontrolled diabetes. 

Insulin (-) hormone sensitive lipase (+) glucose utilization (glycolysis) and acetyl CoA production for lipogenesis. 

What vitamins are required for acetyl CoA production from p)rruvate ... 

Fatty acid oxidation Acetyl-CoA production Ketone body synthesis Fatty acid elongation... 

Phosphoglyceric acid, an oxidation product of serine, can be withdrawn from the pathway much as C4 and C5 acids are withdrawn from the TCA cycle (Jahnke et al. 1999). The acetyl-CoA product can reenter the cycle and lead to the production of succinate for use in biosyntheses (White 1995, p. 265). 

Muscle fuel utilization at rest is dependent on the serum levels of glucose, amino acids, and fatty acids. If blood glucose and amino acids are elevated, glucose will be converted to glycogen, and branched-chain amino acid metabolism will be high. Fatty acids will be used for acetyl CoA production and will satisfy the energy needs of the muscle under these conditions. 

Acetyl-CoA production Muscle and liver Increases Pyruvate dehydrogenase... 

EXAMPLE 13.17 In skeletal muscle, the rate of acetyl-CoA production via 5-oxidation cannot exceed the rate of consumption of acetyl-CoA via the Krebs cycle for extended periods. This is so because a constant rate of CoA supply is necessary for both the conversion of fatty acids to fatty-acyl CoA and the cleavage of acetyl-CoA molecules from fatty-acyl chains in P-oxidation. The CoA concentration in the mitochondrial matrix falls unless CoA is regenerated via citrate synthase in the first step of the Krebs cycle. 

P Oxidation pathway also occur within the glyoxysome so that acetyl-CoA production is directly linked to the glyoxylate cycle. Such species of... 

Ketogenesis (KB synthesis) takes place when acetyl CoA production exceeds the oxidative capacity of the liver. The acetyl CoA is derived from FA KBs can then be transported to other tissues where they are reconverted back to acetyl CoA and oxidized in the TCA cycle. 

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