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Information about Threonine


Threonine

Systematic (IUPAC) name
(2S,3R)-2-Amino-3-hydroxybutanoic acid
Identifiers
CAS number72-19-5
PubChem        6288
Chemical data
FormulaC4H9NO3 
Mol. weight119.12 g/mol
SMILESC[C@@H](O)[C@H](N)C(O)=O
Complete data


Threonine (abbreviated as Thr or T)[1] is an α-amino acid with the chemical formula HO2CCH(NH2)CH(OH)CH3. Its codons are ACU and ACA. This essential amino acid is classified as polar. Together with serine and tyrosine, threonine is one of three proteinogenic amino acids bearing an alcohol group.

The threonine residue is susceptible to numerous posttranslational modifications. The hydroxy side chain can undergo O-linked glycosylation. In addition, threonine residues undergo phosphorylation through the action of a threonine kinase. In its phosphorylated form, it can be referred to as phosphothreonine.

Allo-threonine

With two chiral centers, threonine can exist in four possible stereoisomers, or two possible diastereomers ofL-threonine. However, the name L-threonine is used for one single enantiomer, (2S,3R)-2-amino-3-hydroxybutanoic acid. The second diastereomer (2S,3S), which is rarely present in nature, is calledL-allo-threonine.

Biosynthesis

As an essential amino acid, threonine is not synthesized in humans, hence we must ingest threonine in the form of threonine-containing proteins. In plants and microorganisms, threonine is synthesized from aspartic acid via α-aspartyl-semialdehyde and homoserine. Homoserine undergoes O-phosphorylation; this phosphate ester undergoes hydrolysis concomitant with relocation of the OH group.[2] Enzymes involved in a typical biosynthesis of threonine include:
  1. aspartokinase
  2. α-aspartate semialdehyde dehydrogenase
  3. homoserine dehydrogenase
  4. homoserine kinase
  5. threonine synthase.


Enlarge picture
Threonine biosynthesis

Metabolism

Threonine is metabolized in two ways:
  • It is converted to pyruvate via Threonine Dehydrogenase. An intermediate in this pathway can undergo thiolysis with CoA to produce Acetyl-CoA and glycine.
  • In humans, it is converted to alpha-ketobutyrate in a less common pathway via the enzyme Serine dehydratase, and thereby enters the pathway leading to succinyl-CoA.

Sources

Foods high in threonine include cottage cheese, poultry, fish, meat, lentils, and sesame seeds.

Racemic threonine can be prepared from crotonic acid by alpha-functionalization using mercury(II) acetate.[3]

References

1. ^ IUPAC-IUBMB Joint Commission on Biochemical Nomenclature. Nomenclature and Symbolism for Amino Acids and Peptides. Recommendations on Organic & Biochemical Nomenclature, Symbols & Terminology etc. Retrieved on 2007-05-17.
2. ^ Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. ISBN 1-57259-153-6.
3. ^ Carter, H. E.; West, H. D. (1955). "dl-Threonine". Org. Synth.; Coll. Vol. 3: 813.  

External links


 •  • [ e]
Major families of biochemicals
Peptides | Amino acids | Nucleic acids | Carbohydrates | Lipids | Terpenes | Carotenoids | Tetrapyrroles | Enzyme cofactors | Steroids | Flavonoids | Alkaloids | Polyketides | Glycosides
Analogues of nucleic acids:The 20 Common Amino AcidsAnalogues of nucleic acids:
Alanine (dp) | Arginine (dp) | Asparagine (dp) | Aspartic acid (dp) | Cysteine (dp) | Glutamic acid (dp) | Glutamine (dp) | Glycine (dp) | Histidine (dp) | Isoleucine (dp) | Leucine (dp) | Lysine (dp) | Methionine (dp) | Phenylalanine (dp) | Proline (dp) | Serine (dp) | Threonine (dp) | Tryptophan (dp) | Tyrosine (dp) | Valine (dp)
IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. It is developed and kept up to date under the auspices of the International Union of Pure and Applied Chemistry (IUPAC).
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CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. They are also referred to as CAS numbers, CAS RNs or CAS #s.
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PubChem is a database of chemical molecules. The system is maintained by the National Center for Biotechnology Information (NCBI), a component of the National Library of Medicine, which is part of the United States National Institutes of Health (NIH).
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A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. A chemical formula is also a short way of showing how a chemical reaction occurs.
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4, 2
(mildly acidic oxide)
Electronegativity 2.55 (Pauling scale)
Ionization energies
(more) 1st: 1086.5 kJmol−1
2nd: 2352.6 kJmol−1
3rd: 4620.5 kJmol−1

Atomic radius 70 pm
Atomic radius (calc.
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1, −1
(amphoteric oxide)
Electronegativity 2.20 (Pauling scale) More

Atomic radius 25 pm
Atomic radius (calc.) 53 pm
Covalent radius 37 pm
Van der Waals radius 120 pm
Miscellaneous

Thermal conductivity (300 K) 180.
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3, 5, 4, 2
(strongly acidic oxide)
Electronegativity 3.04 (Pauling scale)
Ionization energies
(more) 1st: 1402.3 kJmol−1
2nd: 2856 kJmol−1
3rd: 4578.1 kJmol−1

Atomic radius 65 pm
Atomic radius (calc.
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2, −1
(neutral oxide)
Electronegativity 3.44 (Pauling scale)
Ionization energies
(more) 1st: 1313.9 kJmol−1
2nd: 3388.3 kJmol−1
3rd: 5300.5 kJmol−1

Atomic radius 60 pm
Atomic radius (calc.
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molecular mass (abbreviated Mr) of a substance, formerly also called molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12).
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smiles

File extension: .smi
Type of format: chemical file format

The simplified molecular input line entry specification or SMILES
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The complete data for Threonine

General information

Chemical formula: C

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amino acid is a molecule that contains both amine and carboxyl functional groups. In biochemistry, this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent.
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A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. A chemical formula is also a short way of showing how a chemical reaction occurs.
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genetic code is the set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins (amino acid sequences) by living cells.
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An essential amino acid or indispensable amino acid is an amino acid that cannot be synthesized de novo by the organism (usually referring to humans), and therefore must be supplied in the diet.

Essentiality vs.


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Chemical polarity, also known as bond polarity or simply polarity, is a concept in chemistry which describes how equally bonding electrons are shared between atoms.
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Serine (abbreviated as Ser or S)[1] is an organic compound with the formula HO2CCH(NH2)CH2OH. It is one of the 20 naturally occurring proteinogenic amino acids. Its codons are UCU, UCC, UCA, UCG, AGU and AGC.
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Tyrosine (abbreviated as Tyr or Y)[1] or 4-hydroxyphenylalanine, is one of the 20 amino acids that are used by cells to synthesize proteins. It is a non-essential amino acid and it is found in large quantities in casein.
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Post-translational modification (PTM) is the chemical modification of a protein after its translation. It is one of the later steps in protein biosynthesis for many proteins. A protein (also called a polypeptide) is a chain of amino acids.
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side chain in organic chemistry and biochemistry is a part of a molecule that is attached to a core structure. An R group is a generic label for a side chain which can be anything; however, it is typically stable and covalently linked to the adjoining atom.
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Glycosylation is the process or result of addition of saccharides to proteins and lipids. The process is one of four principal co-translational and post-translational modification steps in the synthesis of membrane and secreted proteins and the majority of proteins synthesized in
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Phosphorylation is the addition of a phosphate (PO4) group to a protein molecule or a small molecule. Another way to define it would be the introduction of a phosphate group into an organic molecule.
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In chemistry and biochemistry, a kinase, alternatively known as a phosphotransferase, is a type of enzyme that transfers phosphate groups from high-energy donor molecules, such as ATP, to specific target molecules (substrates); the process is termed phosphorylation
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The term chiral (pronounced /ˈkaɪɹ(ə)l̩/) is used to describe an object that is non-superimposable on its mirror image. In terms of chemistry, such objects are usually molecules.
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Stereoisomers are isomeric molecules whose atomic connectivity is the same but whose atomic arrangement in space is different.

Enantiomers

Main article: enantiomer

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Diastereomers (or diastereoisomers) are stereoisomers that are not enantiomers (mirror images of each other). Diastereomers can have different physical properties and different reactivity.
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In chemistry, enantiomers (from the Greek ἐνάντιος, opposite, and μέρος, part or portion) are stereoisomers that are nonsuperimposable complete mirror images of each other, much as one's left and right hands
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Aspartic acid or aspartate (abbreviated as Asp or D; Asx or B represent either aspartic acid or asparagine)[1] is an α-amino acid with the chemical formula HO2CCH(NH2)CH2CO2H.
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Homoserine is an α-amino acid with the chemical formula HO2CCH(NH2)CH2CH2OH. L-Homoserine is not one of the common amino acids encoded by DNA.
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Esters are a class of chemical compounds and functional groups. Esters consist of an inorganic or organic acid in which at least one -OH (hydroxy) group is replaced by an -O-alkyl (alkoxy) group.
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