Direct tryptic cleavage in bone tissue followed by LC-MS/MS as a first step towards routine characterization of proteins embedded in alveolar bones

Abstract While methods like radiology or histology are routinely used in oral surgery, a simple and effective method for characterization of alveolar bones at the molecular level is missing. This is primarily due to the fact that proteomic analysis of hard tissue represents a serious analytical challenge. In this study, we developed a simple technique for the proteomic characterization of bone tissue in the field of oral surgery. After a prewashing step with different solvents, specific digestion with trypsin was performed directly in porcine alveolar bone tissues without the prior reduction and alkylation of disulfide bonds. The released peptides were then analyzed using liquid chromatography-tandem mass spectrometry. When 2-propanol was used in the pre-incubation step, this approach identified 487 proteins in the maxillary (upper jaw) bone and 443 proteins in the mandibular (lower jaw) bone, 40 of each being specifically ascribed to bone tissue. This suggests that routine use of our technique can provide deeper insights into the field of oral surgery at the molecular level. Furthermore, it could also have diagnostic potential in differentiating between the proteomic patterns of healthy and pathological alveolar bone tissue. The mass spectrometry proteomics data are available via ProteomeXchange with identifier PXD018836.