出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/06/11 00:00:15」(JST)
| L-アスパラギン | |
|---|---|
|
IUPAC名
Asparagine |
|
|
別称
2-Amino-3-carbamoylpropanoic acid
|
|
| 識別情報 | |
| CAS登録番号 | 70-47-3 |
| PubChem | 236 |
| ChemSpider | 6031 |
| UNII | 7NG0A2TUHQ |
| EINECS番号 | 200-735-9 |
| KEGG | C00152 |
| ChEMBL | CHEMBL58832 |
|
SMILES
|
|
|
InChI
|
|
| 特性 | |
| 化学式 | C4H8N2O3 |
| モル質量 | 132.12 g mol−1 |
| 酸解離定数 pKa | 2.02 (カルボキシル基), 8.8 (アミノ基)[1] |
| 特記なき場合、データは常温 (25 °C)・常圧 (100 kPa) におけるものである。 | |
アスパラギン (NH2COCH2CH(COOH)NH2) とは、アミノ酸のひとつで、2-アミノ-3-カルバモイルプロピオン酸のこと。 スペルはasparagineで、略号はNあるいはAsn。アスパラガスからはじめて単離されたことによりこの名がついた。アスパラガスを食べた後尿から独特の匂いがすることがあるが、それはこの物質の代謝副産物に起因する。[2]
中性極性側鎖アミノ酸に分類される。蛋白質構成アミノ酸のひとつで、非必須アミノ酸。グリコーゲン生産性を持つ。コドンはAAUまたはAACである。
アスパラギンは1806年、フランスのルイ＝ニコラ・ヴォークランとピエール＝ジャン・ロビケ(当時は助手)によりアスパラガスの汁から結晶として単離され、単離された最初のアミノ酸となった。[3][4]
1809年、ピエール＝ジャン・ロビケは甘草の根からもアスパラギン様物質を単離したが、1828年、それはアスパラギンであったことが確認された。[5]
アスパラギンの側鎖はペプチド骨格と水素結合を形成することができる。つまり、他のペプチド骨格の代わりに水素結合サイトを埋めることができる。そのため、この残基はαヘリックスの始点、終点、βシートのターンで見られる。構造の類似したグルタミンは立体配座エントロピーが大きいため、このような機能は持たない。
また、アスパラギンはタンパクのN-グリコシル化の標的となる。
生体内では、アスパラギン酸からアスパラギンシンテターゼにより生合成される。また、アスパラギナーゼによりアスパラギン酸とアンモニアに分解される。
|accessdate= (help)
|
|||||||||||||||||||||||||||||||
| Names | |
|---|---|
| IUPAC name
Asparagine
|
|
| Other names
2-Amino-3-carbamoylpropanoic acid
|
|
| Identifiers | |
|
CAS Registry Number
|
70-47-3 Y |
| ChEBI | CHEBI:17196 Y |
| ChEMBL | ChEMBL58832 Y |
| ChemSpider | 6031 Y |
| DrugBank | DB03943 Y |
| EC number | 200-735-9 |
|
InChI
|
|
| Jmol-3D images | Image Image |
| KEGG | C00152 Y |
| PubChem | 236 |
|
SMILES
|
|
| UNII | 7NG0A2TUHQ Y |
| Properties | |
|
Chemical formula
|
C4H8N2O3 |
| Molar mass | 132.12 g·mol−1 |
| Appearance | white crystals |
| Density | 1.543 g/cm3 |
| Melting point | 234 °C (453 °F; 507 K) |
| Boiling point | 438 °C (820 °F; 711 K) |
|
Solubility in water
|
2.94 g/100 mL |
| Solubility | soluble in acid, alkali negligible in methanol, ethanol, ether, benzene |
| log P | -3.82 |
| Acidity (pKa) | 2.02 (carboxyl), 8.80 (amino)[1] |
| Structure | |
| Crystal structure | orthorhomic |
| Thermochemistry | |
|
Std enthalpy of
formation (ΔfH |
-789.4 kJ/mol |
| Hazards | |
| Safety data sheet | See: data page Sigma-Alrich |
| NFPA 704 |
0
1
0
|
| Flash point | 219 °C (426 °F; 492 K) |
| Supplementary data page | |
|
Structure and
properties |
Refractive index (n), Dielectric constant (εr), etc. |
|
Thermodynamic
data |
Phase behaviour solid–liquid–gas |
|
Spectral data
|
UV, IR, NMR, MS |
|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|
|
| Y verify (what is: Y/N?) | |
| Infobox references | |
Asparagine (abbreviated as Asn or N) is one of the 20 most-common natural amino acids on Earth. It has carboxamide as the side-chain's functional group. It is not an essential amino acid. Its codons are AAU and AAC.[2]
A reaction between asparagine and reducing sugars or reactive carbonyls produces acrylamide (acrylic amide) in food when heated to sufficient temperature. These products occur in baked goods such as French fries, potato chips, and toasted bread.
Asparagine was first isolated in 1806 in a crystalline form by French chemists Louis Nicolas Vauquelin and Pierre Jean Robiquet (then a young assistant) from asparagus juice,[3][4] in which it is abundant, hence the chosen name. It was the first amino acid to be isolated.
Three years later, in 1809, Pierre Jean Robiquet identified a substance from liquorice root with properties he qualified as very similar to those of asparagine, and that Plisson identified in 1828 as asparagine itself.[5]
Since the asparagine side-chain can form hydrogen bond interactions with the peptide backbone, asparagine residues are often found near the beginning and the end of alpha-helices, and in turn motifs in beta sheets. Its role can be thought as "capping" the hydrogen bond interactions that would otherwise be satisfied by the polypeptide backbone. Glutamines, with an extra methylene group, have more conformational entropy and thus are less useful in this regard.
Asparagine also provides key sites for N-linked glycosylation, modification of the protein chain with the addition of carbohydrate chains. Typically, a carbohydrate tree can solely be added to an asparagine residue if the latter is flanked on the C side by X-serine or X-threonine, where X is any amino acid with the exception of proline.[6]
Asparagine is not essential for humans, which means that it can be synthesized from central metabolic pathway intermediates and is not required in the diet.
Asparagine is found in:
The precursor to asparagine is oxaloacetate. Oxaloacetate is converted to aspartate using a transaminase enzyme. The enzyme transfers the amino group from glutamate to oxaloacetate producing α-ketoglutarate and aspartate. The enzyme asparagine synthetase produces asparagine, AMP, glutamate, and pyrophosphate from aspartate, glutamine, and ATP. In the asparagine synthetase reaction, ATP is used to activate aspartate, forming β-aspartyl-AMP. Glutamine donates an ammonium group, which reacts with β-aspartyl-AMP to form asparagine and free AMP.
Asparagine usually enters the citric acid cycle in humans as malate.[citation needed] In bacteria, the degradation of asparagine leads to the production of oxaloacetate which is the molecule which combines with citrate in the citric acid cycle (Kreb's cycle). Asparagine is hydrolyzed to aspartate by asparaginase. Aspartate then undergoes transamination to form glutamate and oxaloacetate from alpha-ketogluterate.
Asparagine is required for development and function of the brain.[medical citation needed] It also plays an important role in the synthesis of ammonia.
The addition of N-acetylglucosamine to asparagine is performed by oligosaccharyltransferase enzymes in the endoplasmic reticulum.[7] This glycosylation is important both for protein structure[8] and protein function.[9]
|accessdate= requires |url= (help)
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.
| リンク元 | 「アスパラギン」「N」 |
| 拡張検索 | 「peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine amidase」「asparagine-tRNA ligase」「asparagine residue」「L-asparagine」 |
-CH2-CO-NH2
アスパラギンアミダーゼ