Figure 2: A reduced availability of dietary carbohydrates leads to an increased liver production of KBs. The liver cannot utilize KBs because it lacks the mitochondrial enzyme succinyl-CoA: 3-ketoacid (oxoacid) CoA transferase (SCOT) necessary for activation of acetoacetate to acetoacetyl-CoA. KBs are utilized by tissues, in particular by brain. KBs enter the citric acid cycle after being converted to acetyl-CoA by succinyl-CoA: 3-CoA transferase (SCOT) and methylacetoacetyl-CoA thiolase (MAT).