A preliminary study of the decline in solubility of ancient silk protein

Abstract

Recently, proteomics, bioinformatics and other experimental techniques have been increasingly applied to the research of silk cultural relics. Most methods in proteomics require the preparation of silk protein solutions. Therefore, the dissolution of silk protein has become a difficult prerequisite for biotechnical applications in ancient silk research. However, it was found that the solubility of silk protein in ancient silk was significantly lower than that in modern silk. In this study, archaeological silk (Chinese Warring States period, 770BCE-476BCE), thermally aged silk and modern silk were selected to observe the decline in solubility of silk protein. Structural changes in the silk protein degradation process were analyzed by ATR-FTIR and SDS-PAGE. The experimental results suggest that the decline in the solubility of ancient silk is probably related to the mechanism of degradation of silk fibroin. The amorphous regions in ancient silk protein degraded first, and the loss of these proteins directly decreased the silk protein swelling ratios. Without enough amorphous regions, it was difficult for the ions in solution to enter the crystalline regions and difficult for the ions to interact with silk protein molecules. These changes led to a decline in solubility of ancient silk protein. This study provides basic data to improve the solubility of ancient silk and contribute to the analysis and conservation of ancient silk artifacts.