Wikipedia
Felinine, also known as (R)-2-amino-3-(4-hydroxy-2-methylbutan-2-ylthio)propanoic acid, is a chemical compound and amino acid found in cat urine and a precursor via microbial lyase of the putative cat pheromone and thiol called 3-mercapto-3-methylbutan-1-ol (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 and isopentenyl pyrophosphate 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.