Ketolysis is the process of catabolizing

ketone In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...

s, the opposite of

ketogenesis Ketogenesis is the biochemical process through which organisms produce ketone bodies by breaking down fatty acids and ketogenic amino acids. The process supplies energy to certain organs, particularly the brain, heart and skeletal muscle, unde ...

which is the process of synthesizing ketones. Ketolysis provides more energy for ATP synthesis than

fatty acid In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...

oxidation (

beta oxidation In biochemistry and metabolism, beta oxidation (also β-oxidation) is the catabolic process by which fatty acid molecules are broken down in the cytosol in prokaryotes and in the mitochondria in eukaryotes to generate acetyl-CoA. Acetyl-CoA enter ...

). Ketogenesis occurs primarily in the

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

, whereas ketolysis occurs in non-liver cells, especially in the

heart The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrie ...

brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...

, and

skeletal muscle Skeletal muscle (commonly referred to as muscle) is one of the three types of vertebrate muscle tissue, the others being cardiac muscle and smooth muscle. They are part of the somatic nervous system, voluntary muscular system and typically are a ...

. The

SCOT Scottish people or Scots (; ) are an ethnic group and nation native to Scotland. Historically, they emerged in the early Middle Ages from an amalgamation of two Celtic peoples, the Picts and Gaels, who founded the Kingdom of Scotland (or ...

enzyme (aka thiophorase) is required for ketolysis, and is present in the

mitochondria A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is us ...

of all mammalian cells except for

hepatocyte A hepatocyte is a cell of the main parenchymal tissue of the liver. Hepatocytes make up 80% of the liver's mass. These cells are involved in: * Protein synthesis * Protein storage * Transformation of carbohydrates * Synthesis of cholesterol, bi ...

s. Although type II cells of the pulmonary alveolus possess

monocarboxylate transporter The monocarboxylate transporters, or MCTs, are a family of proton-linked plasma membrane transporters that carry molecules having one carboxylate group (monocarboxylates), such as lactate, pyruvate, and ketones across biological membranes. Acetat ...

s to transport of

beta hydroxybutyrate Beta (, ; uppercase , lowercase , or cursive ; or ) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Ancient Greek, beta represented the voiced bilabial plosive . In Modern Greek, it represen ...

precursors into the cytoplasm, the absence of ketolytic enzymes results in the cells being unable to catabolize the beta hydroxybutyrate. The cardioprotective effects of

SGLT2 inhibitor SGLT2 inhibitors (also called gliflozins or flozins) are a class of medications that inhibit sodium-glucose transport proteins in the nephron (the functional units of the kidney), unlike SGLT1, SGLT1 inhibitors that perform a similar function in ...

s have been attributed to the elevated ketone levels and increased ketolysis.

The Ketolytic Pathway

References

{{Reflist Medical terminology