High-performance liquid chromatography-mass spectrometry of an osteocalcin derivative

High-performance liquid chromatography (HPLC) was combined on-line with electrospray ionization mass spectrometry (ESI-MS) for structural analysis of a synthetic osteocalcin derivative and its degradation products. Initial determination of amino acid sequence of the synthetic peptide was performed after tryptic degradation. Hydrolytic degradation of the osteocalcin derivative was studied under different pH conditions: pH 2, pH 7 and pH 10 at 60 degrees C up to 20 h. According the HPLC-ESI-MS results, the chemical stability was dependent on pH. Two major degradation products and a number of other fragments were obtained in acidic solution, whereas the osteocalcin molecule was rather stable in neutral and alkaline conditions.