Contents
Why is propionyl-CoA converted to succinyl-CoA?
Within the citric acid cycle in humans, propionyl-CoA, which interacts with oxaloacetate to form methylcitrate, can also catalyzed into methylmalonyl-CoA through carboxylation by propionyl-CoA carboxylase (PCC). Methylmalonyl-CoA is later transformed to succinyl-CoA to be further used in the tricarboxylic acid cycle.
What are the specialized enzymes involved in the conversion of propionyl-CoA to succinyl-CoA?
The biotin-dependent enzyme propionyl-CoA carboxylase converts propionyl-CoA into D-methylmalonyl-CoA, which is then racemized into L-methylmalonyl-CoA and isomerized into succinyl-CoA, a Krebs cycle intermediate.
How does propionyl-CoA enters TCA cycle?
Metabolic pathway. Propionyl-CoA carboxylase (PCC) catalyzes the conversion of propionyl-CoA to methylmalonyl-CoA, which enters the Krebs cycle via succinyl-CoA. Sources of propionate include: valine, isoleucine, threonine, methionine, odd-chain fatty acids, and cholesterol.
How is succinyl-CoA generated?
Succinyl CoA can be formed from methylmalonyl CoA through the utilization of deoxyadenosyl-B12 (deoxyadenosylcobalamin) by the enzyme methylmalonyl-CoA mutase. This reaction, which requires vitamin B12 as a cofactor, is important in the catabolism of some branched-chain amino acids as well as odd-chain fatty acids.
Can propionyl CoA be converted to glucose?
Propionyl-CoA is converted to succinyl-CoA, which is oxidized or converted to glucose by way of oxaloacetate and pyruvate (gluconeogenesis; Chapter 14). Succinyl-CoA may also form Δ-aminolevulinate, a precursor of porphyrin biosynthesis (Chapter 17).
What is propionyl CoA converted to?
Propionyl-CoA is converted to succinyl-CoA, which is oxidized or converted to glucose by way of oxaloacetate and pyruvate (gluconeogenesis; Chapter 15). Succinyl-CoA may also form δ-aminolevulinate, a precursor of porphyrin biosynthesis (Chapter 29).
What is succinyl-CoA used for?
Succinyl-CoA synthetase (SCS) is the only mitochondrial enzyme capable of ATP production via substrate level phosphorylation in the absence of oxygen, but it also plays a key role in the citric acid cycle, ketone metabolism and heme synthesis.
Is propionyl CoA ketogenic?
Isoleucine is both ketogenic and glucogenic (degradation produces acetyl CoA and propionyl CoA, which is converted to succinyl CoA).
Why is succinyl-CoA important?
The citric acid cycle intermediate succinyl-CoA plays an important role in fatty acid and amino acid metabolism because it is the entry point of odd-chain fatty acids, propionate, and the branched-chain amino acids valine and isoleucine into the citric acid cycle.
How are four amino acids converted into succinyl-CoA?
Four Amino Acids Are Converted into Succinyl-CoA The carbon skeletons of methionine, isoleucine, threonine, and valine are degraded by pathways that yield succinyl-CoA (Fig. 17-30), an intermediate of the citric acid cycle.
How is propionyl CoA converted to β hydroxypropionate?
These two molecules are deemed to be intermediates in valine metabolism. As propionate consists in the form of propionyl-CoA, it was discovered that propionyl-CoA is converted to β-hydroxypropionate through a peroxisomal enzymatic β-oxidation pathway.
How is propionyl CoA converted to glucose in the rumen?
In ruminants, propionate is largely derived from bacterial fermentation in the rumen. Propionyl-CoA is converted to succinyl-CoA, which is oxidized or converted to glucose by way of oxaloacetate and pyruvate (gluconeogenesis; Chapter 15 ).