What happens if oxaloacetate is not present?
TRICARBOXYLIC ACID CYCLE If oxaloacetate is removed from the cycle for glucose synthesis, it must be replaced, since if there is not enough oxaloacetate available to form citrate, the rate of acetyl CoA metabolism, and hence the rate of formation of ATP, will slow down.
Why acetyl-CoA obtained from the metabolism of ketogenic amino acids Cannot be used to synthesize glucose?
Fatty acids and ketogenic amino acids cannot be used to synthesize glucose. The transition reaction is a one-way reaction, meaning that acetyl-CoA cannot be converted back to pyruvate. As a result, fatty acids can’t be used to synthesize glucose, because beta-oxidation produces acetyl-CoA.
What are the source of propionyl-CoA in human?
Important sources of propionyl-CoA are the catabolism of isoleucine, valine, methionine, and threonine (Chapter 17). Cholesterol side chain oxidation also yields propionyl-CoA. Thus, propionyl-CoA is derived from the catabolism of lipids and proteins.
What is the importance of oxaloacetate?
Oxaloacetate, an intermediate in the tricarboxylic acid cycle, plays important roles in regulating mitochondrial function, gluconeogenesis, the urea cycle, and amino acid syntheses.
Why is oxaloacetate important in the citric acid cycle?
Oxaloacetate is an intermediate of the citric acid cycle, where it reacts with acetyl-CoA to form citrate, catalyzed by citrate synthase. It is also involved in gluconeogenesis, the urea cycle, the glyoxylate cycle, amino acid synthesis, and fatty acid synthesis. Oxaloacetate is also a potent inhibitor of complex II.
What problem would arise if the excess acetyl-CoA were not converted to ketone bodies?
Although the excess acetyl-CoA is not toxic, it must be diverted into the formation of ketone bodies: acetone, acetoacetate, and D-(hydroxybutyrate What problem would arise if the excess acetyl-CoA were not converted to ketone bodies? Fatty acid oxidation would stop when all the CoA is bound as acetyl-CoA.
Can acetyl-CoA be converted to ketone bodies?
The accumulation of acetyl-CoA in turn produces excess ketone bodies through ketogenesis. The result is a rate of ketone production higher than the rate of ketone disposal, and a decrease in blood pH. There are some health benefits to ketone bodies and ketogenesis as well.
How is propionyl-CoA produced?
Propionyl-CoA is not only produced from the oxidation of odd-chain fatty acids, but also by the oxidation of amino acids including methionine, valine, isoleucine, and threonine. Cholesterol oxidation, which forms bile acids, also forms propionyl-CoA as a side product.
Which of the following leads to the formation of propionyl-CoA?
As mentioned above, proteins contain the amino acids isoleucine, valine and methionine and the degradation of these amino acids leads to the formation of propionyl-CoA.
What is the fate of propionyl-CoA produced in beta oxidation of odd numbered fatty acid chain?
Mitochondrial β-oxidation of dietary odd-chain fatty acids produces propionyl CoA in addition to acetyl CoA. Propionyl CoA is converted to D-methylmalonyl CoA in a reaction catalyzed by the biotin-dependent propionyl CoA carboxylase.
What is the fate of propionyl-CoA from the oxidation of fatty acids with odd number of carbon?
Propionyl CoA, generated from fatty acids with an odd number of carbons as well as some amino acids, is converted into the citric acid cycle intermediate succinyl CoA.