Global profiling and relative quantifiction of histones, histone PTMs and histone-modifying enzymes in mesenchymal stem cells using LC-MS/MS and a novel PerfectPair mass difference algorithm.

摘要

Over the years, mass spectrometry (MS) has emerged as a powerful analytical technique for the identification of unknown compounds, determination of molecular weights, elucidation of molecular structures and quantification of a wide variety of analytes. Although mass spectrometry has been applied to protein biomarker discovery for at least a decade, one of the most difficult problems has been the precise quantification and characterization of post-translational modifications and isoforms detected in "shotgun" LC-MS/MS experiments. Recently, a different type of MS experiment, selected reaction monitoring (SRM), is increasingly being applied to the measurement of protein biomarkers. Advantages of SRM-based MS experiments include very high throughput, sensitivity, specificity and absolute quantification using internal isotopically labeled standards. SRM experiments are also a powerful technique for the measurement and quantification of post-translational modifications (PTMs) and disease-specific alterations. MS is the only technique that can deliver the specificity required to detect isoforms associated with protein sequence microheterogeneity and many clinically relevant variants. Such assays could potentially be used for disease diagnosis and prognosis, and they are typically robust and selective, even in complex matrices.