Felinine, also known as (R)-2-amino-3-(4-hydroxy-2-methylbutan-2-ylthio)propanoic acid, is a chemical compound found in cat

Cat

The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...

 urine

Urine

Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...

 and a precursor of the putative cat pheromone

Cat pheromone

Cat pheromones are pheromones that are used by cats and other felids for cat communication.- Feline facial pheromone :Feline facial pheromone is a hypothetical pheromone used by cats to mark places, objects, and persons as familiar by rubbing their face on surfaces...

 3-mercapto-3-methylbutan-1-ol

3-Mercapto-3-methylbutan-1-ol

3-Mercapto-3-methylbutan-1-ol, abbreviated as MMB, is a thiol and an alcohol. MMB is a degradation product of felinine in cat urine and is a putative cat pheromone....

 (MMB).
Felinine is excreted by selected Felidae species including bobcats, Chinese desert cats, the kodkod and domestic cats. Felinine synthesis occurs in the liver through a condensation reaction of glutathione

Glutathione

Glutathione is a tripeptide that contains an unusual peptide linkage between the amine group of cysteine and the carboxyl group of the glutamate side-chain...

 and isopentenyl pyrophosphate

Isopentenyl pyrophosphate

Isopentenyl pyrophosphate is an intermediate in the classical, HMG-CoA reductase pathway used by organisms in the biosynthesis of terpenes and terpenoids. IPP is formed from acetyl-CoA via mevalonic acid...

to form 3-mercaptobutanolglutathionine (3-MBG). In the kidney 3-MBG is hydrolysed and felinine partly acetylated. Cauxin assists in the hydrolysis of the dipeptide (felinylglycine) to increase the concentration of urinary felinine .
Urine of domestic cats may contain a series of felinine containing compounds including free felinine, acetylfelinine, felinylglycine and 3-MBG.