ornithine

[ awr-nuh-theen ]

noun

, Biochemistry.

1. an amino acid, H 2 N(CH 2 ) 3 CH(NH 2 )COOH, obtained by the hydrolysis of arginine and occurring as an intermediate compound in the urea cycle of mammals.

ornithine

/ ˈɔːnɪˌθiːn /

noun

1. an amino acid produced from arginine by hydrolysis: involved in the formation of urea in the liver; diaminopentanoic acid. Formula: NH 2 (CH 2 ) 3 CHNH 2 COOH

ornithine

/ ôr′nə-thēn′ /

1. An amino acid not found in proteins, formed by hydrolyzing arginine and important in the formation of urea. Chemical formula: C 5 H 12 N 2 O 2 .

Word History and Origins

Origin of ornithine¹

1880–85; ornith(uric acid) , secreted by birds + -ine ²

Word History and Origins

Origin of ornithine¹

C19: from ornithuric ( acid ) secreted in the urine of birds, from ornitho- + uric

Example Sentences

In fact, two amino acids, lysine and ornithine, became more abundant in the gut after infection.

From Science Daily

By using stable isotope tracers and analyzing gene expression, the researchers showed that S. gordonii releases a substance called ornithine that prompts F. nucleatum to produce more of a molecule called polyamine.

From Science Daily

Tawfik and Metanis demonstrated that functional proteins could have come into being "from short and simple sequences" including an amino acid, ornithine, that does not exist in modern proteins.

From Salon

One possible way to explain this is if the core apoptotic machinery prevents ornithine from entering the mitochondrion and instead diverts it towards spermidine production.

From Nature

Lysine and ornithine have very similar molecular structures, and the authors found that Spe1, the enzyme that decarboxylates ornithine, can also decarboxylate lysine to generate cadaverine.

From Nature