A strategy for identifying species-specific peptide biomarkers in deer-hide gelatin using untargeted and targeted mass spectrometry approaches.

Deer-hide gelatin (DHG) is an important animal-derived traditional Chinese medicine (TCM), which has been applied in TCM for over 400 years. However, it is extremely difficult to distinguish DHG with adulteration or made with other animal skins due to the highly processing procedure. Therefore, a simple strategy for identifying species-specific peptide biomarkers in deer-hide gelatin (DHG) is needed. In the present study, untargeted and targeted mass spectrometry approaches were implemented to analyze comprehensive peptidomic profiles of trypsin-digested animal gelatins. Mathematics set theory was then used to interrogate the relationship between different samples and peptides in the target species set, while the peptides were not considered as species-specific biomarkers in other sets. Two peptides were identified as DHG-specific peptides. Targeted mass spectrometry approach was then used to verify these two peptides. It showed that these two peptides could be used for distinguishing DHG from other animal hide gelatins. The present strategy provides a simple method for peptide biomarker discovery, which can be applied in the identification of specific peptides in some highly processed animal derived traditional Chinese medicines (TCMs). Thus, the present work provides an effective strategy for rapid, simple discovery and application of species-specific peptide biomarkers to ensure animal derived TCMs quality and make them authenticable and traceable.