Comparative proteomic analysis of residual proteins in waterlogged ancient leather

Leather artifacts hold significant historical and cultural value in human civilization. During long-term preservation, ancient relics, especially waterlogged leather artifacts, are susceptible to protein degradation. Therefore, analyses of the structure and protein composition of these ancient relics are crucial for their effective conservation. However, comprehensive research in this field is scarce and urgently needed. In this study, systematic investigations of the structures of fresh vegetable-tanned leather, dried leather artifacts, and waterlogged leather artifacts were performed from multiple perspectives. Compared with fresh vegetable-tanned leather and dry leather artifacts, the deterioration of waterlogged leather artifacts resulted in a darkened color, increased brittleness, and reduced fiber structure. Infrared analyses revealed that the characteristic peaks of the amide II and III bands were nearly absent in waterlogged leather artifacts. The species of the leather artifacts were analyzed using enzyme-linked immunosorbent assay (ELISA). Furthermore, comparative proteomic analysis revealed a markedly reduced repertoire of protein species in waterlogged leather artifacts compared with fresh vegetable-tanned leather. In particular, the number of peptides derived from type I collagen and other structural proteins was substantially diminished. This loss of collagen- and structure-related peptides, together with extensive fiber disintegration, underlies the pronounced morphological deterioration observed in waterlogged leather. By integrating species identification through ELISA with proteomic profiling, we establish a strategy that enables rapid, sensitive, and specific characterization of leather proteins. SIGNIFICANCE: This study integrated stereomicroscopy, scanning electron microscopy (SEM), and fourier transform infrared spectroscopy (FTIR) to systematically characterize morphological and microstructural differences between fresh vegetable-tanned leather and archaeological waterlogged leather artifacts. To further unravel residual proteins, comparative proteomic profiling was implemented to identify compositional shifts in collagenous proteins resulting from prolonged waterlogged burial conditions. A multidisciplinary approach was used to assess the characteristics of waterlogged leather artifacts.