(redirected from Thr)
Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.


(thrē`ənēn), organic compound, one of the 22 α-amino acidsamino acid
, any one of a class of simple organic compounds containing carbon, hydrogen, oxygen, nitrogen, and in certain cases sulfur. These compounds are the building blocks of proteins.
..... Click the link for more information.
 commonly found in animal proteins. Only the l-stereoisomer appears in mammalian protein. It is one of several essential amino acids needed in the diet; human beings cannot synthesize it from simpler metabolites. Young adults need about 14 mg of this amino acid per day per kilogram (6 mg per lb) of body weight. Although threonine participates in many reactions in bacteria, including the biosynthesis of vitamin B12 and isoleucineisoleucine
, organic compound, one of the 20 amino acids commonly found in animal proteins. Only the l-stereoisomer appears in mammalian protein.
..... Click the link for more information.
, its metabolic role in higher animals, including man, remains obscure. It is known only as a constituent of proteins, and even in that form it is relatively unreactive. In spite of the fact that its side chain has a hydroxyl group similar to that of serineserine
, organic compound, one of the 20 amino acids commonly found in animal proteins. Only the l-stereoisomer appears in mammalian protein.
..... Click the link for more information.
, there is no indication that it participates in the catalytic functions of any enzyme. Threonine was isolated from the protein fibrin in 1935 and synthesized in the same year.



α-amino-β-hydroxybutyric acid, a natural amino acid, CH3CH(OH)CH(NH2)COOH. It exists in four optically active forms and two racemates (L-, D-, and DL-threonine and L-, D-, and DL-allothreonine). Natural L-threonine was isolated in 1935 from acid hydrolysates of fibrin. L-threonine constitutes 2–6 percent of all natural proteins, except protamines.

Threonine is an essential amino acid. The daily requirement for adults is 0.5 g, and for children up to the age of 7, about 3 g. The precursor of L-threonine during biosynthesis in plants and microorganisms is aspartic acid. This multistage enzymic process is regulated according to the feedback principle: excess threonine inhibits the first enzyme on the path to the biosynthesis of threonine. There are various possible pathways for the decomposition of threonine in the body; they lead to the formation of a-ketobutyric acid, acetaldehyde, and glycine, as well as pyruvic acid.

A method for the chemical synthesis of L-threonine from acetaldehyde and glycine has been developed.


Meister, A. Biokhimiia aminokislot. Moscow, 1961. (Translated from English.)



CH3CHOHCH(NH2)COOH A crystalline α-amino acid considered essential for normal growth of animals; it is biosynthesized from aspartic acid and is a precursor of isoleucine in microorganisms.
References in periodicals archive ?
These physician-imposed restrictions may partly explain why THR doesn't appear to provide patients with the same level of activity as resurfacing does, explains Trevor Murray, MD, a Cleveland Clinic orthopaedic surgeon.
THR & Associates has 800 employees and expects to hire 1,500 more by 2013, Kelly said.
At this temperature, the solder paste becomes fluid and fills the holes by capillary action, soldering the THR components to the circuit board.
For older individuals, a conventional THR is generally more appropriate.
THR serves one of every five people living in these counties for inpatient hospital care.
Until THR discovered a secure WAN solution, however, providing physicians with secure Internet access to patient information and real-time diagnostics from their homes and remote offices posed a difficult challenge.
Since 1997, the annual IS budget at THR has been trimmed by 25 percent.
The financing was arranged for THR Products Corporation, a custom manufacturer of architectural cast stone and GFR products.
What's more, the study showed that hospital volume has significant associations with key outcomes of primary THR such as mortality infection, dislocation, and readmission to the hospital.
They found THR to be "a highly successful treatment for pain and disability, with most patients having an excellent prognosis for long-term improvement in symptoms and physical function.