Arginine

Arginine

Skeletal formula of arginine
Ball-and-stick model Space-filling model
Names
IUPAC names Arginine
Other names 2-Amino-5-guanidinopentanoic acid
Identifiers
CAS Number	L: 74-79-3 Y D/L: 7200-25-1 Y D: 157-06-2 Y L HCl: 1119-34-2 Y
3D model (JSmol)	L: Interactive image D: Interactive image L HCl: Interactive image L Zwitterion: Interactive image
Beilstein Reference	1725411, 1725412 D, 1725413 L
ChEBI	L: CHEBI:29016 Y
ChEMBL	L: ChEMBL1485 Y D: ChEMBL212301 Y
ChemSpider	L: 6082 Y D/L: 227 Y D: 64224 Y
DrugBank	L: DB00125 Y
ECHA InfoCard	100.000.738
EC Number	L: 230-571-3
Gmelin Reference	364938 D
IUPHAR/BPS	L: 721
KEGG	L: C02385 Y
MeSH	Arginine
PubChem CID	L: 6322 D/L: 232 D: 71070
RTECS number	L: CF1934200 L
UNII	L: 94ZLA3W45F Y D/L: FL26NTK3EP Y D: R54Z304Z7C Y L HCl: F7LTH1E20Y Y
CompTox Dashboard (EPA)	L: DTXSID6041056
InChI InChI=1S/C6H14N4O2/c7-4(5(11)12)2-1-3-10-6(8)9/h4H,1-3,7H2,(H,11,12)(H4,8,9,10)/t4-/m0/s1 Y Key: ODKSFYDXXFIFQN-BYPYZUCNSA-N Y D/L: Key: ODKSFYDXXFIFQN-UHFFFAOYSA-N D: Key: ODKSFYDXXFIFQN-SCSAIBSYSA-N
SMILES L: C(C[C@@H](C(=O)O)N)CNC(=N)N D/L: C(CC(C(=O)O)N)CNC(=N)N D: C(C[C@H](C(=O)O)N)CNC(=N)N L HCl: [Cl-].NC(CCCNC(N)=[NH2+])C([O-])=O L Zwitterion: NC(CCCNC(N)=[NH2+])C([O-])=O
Properties
Chemical formula	C6H14N4O2
Molar mass	174.204 g·mol−1
Appearance	White crystals
Odor	Odourless
Melting point	260 °C; 500 °F; 533 K
Boiling point	368 °C (694 °F; 641 K)
Solubility in water	14.87 g/100 mL (20 °C)
Solubility	slightly soluble in ethanol insoluble in ethyl ether
log P	−1.652
Acidity (pKa)	2.18 (carboxyl), 9.09 (amino), 13.8 (guanidino)
Thermochemistry
Heat capacity (C)	232.8 J K−1 mol−1 (at 23.7 °C)
Std molar entropy (S⦵298)	250.6 J K−1 mol−1
Std enthalpy of formation (ΔfH⦵298)	−624.9–−622.3 kJ mol−1
Std enthalpy of combustion (ΔcH⦵298)	−3.7396–−3.7370 MJ mol−1
Pharmacology
ATC code	B05XB01 (WHO) S
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H319
Precautionary statements	P305+P351+P338
Lethal dose or concentration (LD, LC):
LD50 (median dose)	5110 mg/kg (rat, oral)
Safety data sheet (SDS)	L-Arginine
Related compounds
Related alkanoic acids	N-Methyl-D-aspartic acid beta-Methylamino-L-alanine Guanidinopropionic acid Theanine Pantothenic acid
Related compounds	Panthenol
Supplementary data page
Arginine (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Arginine is the amino acid with the formula (H₂N)(HN)CN(H)(CH₂)₃CH(NH₂)CO₂H. The molecule features a guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO₂⁻) and both the amino and guanidino groups are protonated, resulting in a cation. Only the l-arginine (symbol Arg or R) enantiomer is found naturally.^[1] Arg residues are common components of proteins. It is encoded by the codons CGU, CGC, CGA, CGG, AGA, and AGG.^[2] The guanidine group in arginine is the precursor for the biosynthesis of nitric oxide.^[3] Like all amino acids, it is a white, water-soluble solid.

The one-letter symbol R was assigned to arginine for its phonetic similarity.^[4]