Arginine

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. Arg residues are common components of proteins. It is encoded by the codons CGU, CGC, CGA, CGG, AGA, and AGG. The guanidine group in arginine is the precursor for the biosynthesis of nitric oxide. Like all amino acids, it is a white, water-soluble solid.

Arginine

Skeletal formula of arginine
Space-filling model
Names
IUPAC names
Arginine
Other names
2-Amino-5-guanidinopentanoic acid
Identifiers
3D model (JSmol)
3DMet
1725411, 1725412 D, 1725413 L
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.738
EC Number
  • L: 230-571-3
364938 D
KEGG
MeSH Arginine
PubChem CID
RTECS number
  • L: CF1934200 L
UNII
  • 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
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)
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
232.8 J K−1 mol−1 (at 23.7 °C)
Std molar
entropy (S298)
250.6 J K−1 mol−1
Std enthalpy of
formation fH298)
−624.9–−622.3 kJ mol−1
−3.7396–−3.7370 MJ mol−1
Pharmacology
B05XB01 (WHO) S
Hazards
GHS labelling:
Warning
H319
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
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

The one-letter symbol R was assigned to arginine for its phonetic similarity.

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