Proteomic Analysis of Collagen: a Mass Spectrometry Approach to Material Identification of Shadow Puppet Cultural Relics.

Shadow puppets are a popular art form in various regions, including China, Indonesia, and Turkey, and are rich in cultural significance. However, there is a considerable lack of research on the materials, diseases and conservation techniques related to shadow puppet relics. Material identification is the basis for understanding the production process of ancient shadow puppet relics and evaluating their deterioration degree. The microscopic morphology and infrared spectroscopy results in our experiments showed that the traditional methods of ancient skin identification were not effective in the shadow puppet samples. In order to achieve accurate identification, we used biological mass-spectrometry in proteomics to examine two puppet relics and commercially available modern shadow puppets. The results showed that the above samples could be detected by mass spectrometry with abundant peptides, including peptides specific for bovine skin. These peptides cannot be found in other commonly used materials for making shadow puppets, including the skins of pig, sheep, deer and horse. It is worth mentioning that we have found the peptides specific to yellow cowhide in two ancient shadow puppet relics samples. Therefore, the proteomic evidence shows that the raw materials of the two shadow puppet relics samples are yellow cowhide. Four modern samples also confirmed the reliability of material identification using proteomics. The proteomic evidence shows that the biological mass spectrometry will contribute to the scientific research of shadow puppet relics and other skin and leather cultural relics.