3oxobutanoylCoA

3-oxobutanoyl-CoA, also known as acetoacetyl-CoA, is a crucial metabolic intermediate in biochemistry. It is a four-carbon compound that plays a significant role in both catabolic and anabolic pathways. In the breakdown of fats, known as beta-oxidation, fatty acids are successively shortened by two-carbon units, ultimately yielding acetyl-CoA. When two molecules of acetyl-CoA condense, acetoacetyl-CoA is formed. This molecule is then further processed or can be converted back into acetyl-CoA.

In the synthesis of fatty acids, acetyl-CoA is the primary building block. Acetoacetyl-CoA is formed as an intermediate during this process, specifically through the condensation of two acetyl-CoA molecules catalyzed by acetyl-CoA carboxylase. This step is a key regulatory point in fatty acid synthesis. Beyond its role in lipid metabolism, acetoacetyl-CoA is also involved in the synthesis of ketone bodies in the liver, particularly during periods of fasting or prolonged exercise when glucose availability is low. These ketone bodies can then be used as an alternative energy source by tissues like the brain and muscles. The interconversion between acetyl-CoA and acetoacetyl-CoA highlights its central position in cellular energy management.