Final answer:
The rate-limiting enzyme in ketone body formation is HMG-CoA synthase, memorably linked with the mnemonic "HMG-CoA ROKS" (option A). This enzyme catalyzes the conversion of excess acetyl CoA into HMG CoA, a precursor to β-hydroxybutyrate, the primary ketone body found in the blood.
Step-by-step explanation:
Rate-Limiting Enzyme in Ketone Body Formation
The rate-limiting enzyme of ketone body formation is HMG-CoA synthase.
In the ketone synthesis reaction, excess acetyl CoA is converted into hydroxymethylglutaryl CoA (HMG CoA), an intermediate that is subsequently converted into β-hydroxybutyrate, the primary ketone body found in the blood. HMG CoA is a precursor of cholesterol and ketone bodies.
The committed step in ketogenesis is the formation of HMG-CoA from acetyl-CoA and acetoacetyl-CoA, catalyzed by HMG-CoA synthase, not to be confused with HMG-CoA reductase which is involved in cholesterol synthesis. This reaction occurs in the mitochondria of liver cells.
The mnemonic that refers to this enzyme is option A) "HMG-CoA ROKS", tying the initial letters of the enzyme to the key word "ROCKS" as a way to remember it. Other key points include ketone body oxidation and the role of ketone bodies as an alternative energy source, especially during times when glucose is scarce.
An overproduction of these ketone bodies can lead to the condition known as diabetic ketoacidosis, which can be detected through symptoms such as sweet or alcohol-like breath odor.