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(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.
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 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.
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, 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.
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, 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.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



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.)


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
All studied parameters were higher for animals supplemented with Thr in ovo (T) (p [less than or equal to] 0.05), but crypt depth was not different (p > 0.05).
In conclusion, we estimate that the dietary Thr requirement is 0.57% to achieve the maximum egg production, egg mass, and feed utilization relative to the egg mass, while a level of 0.58% is required to obtain the maximum egg weight in Longyan ducks from 17-45 wk of age.
Research suggests that the type of implant you have can make a difference to your long-term prognosis after THR (see box below for more).
Also, the actor said that Jake has lost the trust because "he failed with the Maya Pope thing, ran off with Olivia at Fitz's darkest moment and took advantage of that and manipulated her in Fitz's view." Goldwyn told THR that when evidence against Jake surfaces, Fitz's "complicated feelings about Olivia" and the "way Jake has failed him" have made him only trust Rowan.
Analogous to phosphorylation, O-glycosylation is also one of the important PTMs during which N-acetyl-glucosamine (O-GlcNAc) molecule is introduced on Thr or Ser residue by O-GlcNAc transferase (OGT).
The company, which has a major presence on Teesside, has bought the remaining assets - 47 properties - from Terrace Hill Residential (THR), of which it held a 49% interest, a purchase funded by a PS4.6m bank loan and cash from the firm's own resources.
Summary: TEHRAN (FNA)- In an interview with THR, Cindy Lee Garcia talks about the film she thought she was shooting, the fallout from the controversy and how "Master George" became Muslim Prophet Mohammad (PBUH).