Oxidative degradation of antiflammin 2.
OBJECTIVE
To study the oxidation of the methionine residue of antiflammin 2 (HDMNKVLDL, AF2) as a function of pH, buffer concentration, ionic strength, and temperature using different concentrations of hydrogen peroxide and to determine the accessibility of methionine residue to oxidation.


METHODS
Reversed-phase high-performance liquid chromatography (RPHPLC) was used as the main analytical method in determining the oxidation rates of AF2. Calibration curves for AF2 and the oxidation product, methionine sulfoxide of AF2 (Met(O)-3-AF2), were constructed for each measurement using standard materials. Fast Atom Bombardment Mass Spectroscopy (FABMS) was used to characterize the product.


RESULTS
Met(O)-3-AF2 was the only oxidation product detected at pH 3.0 to 8.0. The oxidation rates were independent of buffer concentrations, ionic strength, and pH from 3.0 to 7.0. However, there was an acceleration of the rates at basic pHs, and small amounts of degradation products other than Met(O)-3-AF2 were observed in this alkaline region.


CONCLUSIONS
Oxidation of methionine in AF2 does not cause the biological inactivation reported by other laboratories since this drug is relatively stable under neutral conditions in the absence of oxiding agent.
Ye
J M
JM
Department of Pharmaceutical Sciences, University of Tennessee, Memphis 38163, USA.
Wolfe
J L
JL
D000595:Amino Acid Sequence; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry*; D002021:Buffers; D002135:Calcium-Binding Proteins / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008715:Methionine / Q000737:chemistry; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry*; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000737:chemistry*; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013696:Temperature
D000894:Anti-Inflammatory Agents, Non-Steroidal; D002021:Buffers; D002135:Calcium-Binding Proteins; D009842:Oligopeptides; D010446:Peptide Fragments; C064647:antiflammin P2; D008715:Methionine; D006861:Hydrogen Peroxide