Ribonuclease A

Molecular Formula: C₉H₁₄N₄O₃ 
Molecular Weight: 226.2325 
EINECS: 207-332-7 
Density: 1.375 g/cm³ 
Melting Point: 243 °C (dec.)
Flash Point: 350.7 °C 
Boiling Point: 656.2 °C at 760 mmHg 
Vapour Pressure: 4.08E-18 mmHg at 25 °C 
Enthalpy of Vaporization: 101.53 kJ/mol 
Storage temp.: 2-8 °C
Structure of Ribonuclease A (CAS NO.9001-99-4):
                       
IUPAC Name: 2-(3-Aminopropanoylamino)-3-(1H-imidazol-5-yl)propanoic acid 
Canonical SMILES: C1=C(NC=N1)CC(C(=O)O)NC(=O)CCN
InChI: InChI=1S/C9H14N4O3/c10-2-1-8(14)13-7(9(15)16)3-6-4-11-5-12-6/h4-5,7H,1-3,10H2,(H,11,12)(H,13,14)(H,15,16) 
InChIKey: CQOVPNPJLQNMDC-UHFFFAOYSA-N

The importance of bovine pancreatic Ribonuclease A (CAS NO.9001-99-4) was secured when the Armour & Co. (of hot dog fame) purified a kilogram of it, and gave 10 mg samples away free to any interested scientists. The ability to have a single lot of purified enzyme instantly made RNase the model system for protein studies.Ribonuclease-S, which is RNase A that has been treated with subtilisin, was the third protein to have its structure solved, in 1967. Studies of the oxidative folding of RNase A led Chris Anfinsen to enunciate the thermodynamic hypothesis of protein folding, which states that the folded form of a protein represents the minimum of its free energy.