Enzymes of ketone body utilization in human tissues: protein and messenger RNA levels of succinyl-coenzyme A (CoA):3-ketoacid CoA transferase and mitochondrial and cytosolic acetoacetyl-CoA thiolases.
Level 5 - mechanism / opinion, no new human data
Bench research analyzing human tissue samples (in vitro biochemical/molecular analysis).
PubMed 9380443 · doi:10.1203/00006450-199710000-00013
What was done
The authors quantified polypeptide and mRNA levels of three ketone-utilization enzymes—succinyl-CoA:3-ketoacid CoA transferase (SCOT), mitochondrial acetoacetyl-CoA thiolase (T2), and cytosolic acetoacetyl-CoA thiolase (CT)—across human tissues using quantitative immunoblots and Northern blots.
What was found
Polypeptide and mRNA levels were generally proportional across tissues. CT protein was highest in liver, 4-fold lower in adrenal glands, kidney, brain, and lung, and lowest in skeletal and heart muscle. T2 protein was most abundant in liver, with substantial amounts in kidney, heart, adrenal glands, and skeletal muscle. SCOT was detected in all examined tissues except liver, with highest levels in myocardium, followed by brain, kidney, and adrenal glands. Relative levels of T2 and SCOT were comparable across most tissues, except liver (T2 >> SCOT) and brain (SCOT > T2).
Why it matters
This establishes the baseline anatomical distribution and expression profile of human ketolytic and ketogenic enzymes, helping explain the tissue-specific pathophysiology of hereditary ketoacidosis disorders.
Limits
The abstract does not state the number of human donors, donor demographics, tissue sources, post-mortem intervals, or exact quantitative values with measures of variance.
Cited by
- supports Ketones are produced by mitochondria in the liver, with a minor amount produced by the kidneys, and the biochemical pathway from ketones to mitochondrial metabolism involves fewer enzymes than that of glucose.