The Efficient Extraction Method of Collagen from Deteriorated Leather Artifacts

Abstract

Collagen is the most crucial component of leather artifacts and analyzing collagen can provide vital information for studying and conserving such artifacts. However, collagen in leather artifacts often faces challenges such as degradation, denaturation, and contamination, which make it difficult to achieve an ideal protein extract using traditional extraction methods. This study aimed to find an efficient collagen extraction strategy for aging leather by comparing and improving commonly used methods. The results of comparing different extraction methods indicated that a NaOH solution was highly effective in extracting collagen from aged leather. To determine the optimal conditions for collagen extraction from the NaOH solution, we conducted orthogonal experiments. The results revealed that a NaOH concentration of 0.05 mol/L, a dissolution temperature of 80 °C, and a dissolution time of 12 h were the most favorable conditions. To validate the effectiveness of this method, we performed SDS-PAGE and biological mass spectrometry tests on collagen extracts from leather samples with varying degrees of aging. All collagen extracts exhibited distinct bands in the gel, and the molecular weight of collagen in each sample exceeded 20 kDa. Furthermore, even with a reduced sample mass of 1 mg (micro-destructive sampling), biological mass spectrometry identified 124 peptides in the protein extract. Notably, four of these peptides were unique to cattle hide collagen and were not present in the collagen of pig, sheep, horse, deer, or human skins. These experimental findings confirm the efficacy of the NaOH solution for extracting collagen from aging leather, suggesting that it can serve as a significant method for collagen identification and analysis in leather artifacts.

Keywords: collagen; conservation of cultural relics; extraction of ancient protein; leather artifacts.

Scheme 1

Screening, optimization, and testing of collagen extraction methods for deteriorated leather artifacts.

Figure 1

Microscopic morphological photographs of leather samples with different aging degrees.

Figure 2

The mass difference of leather samples by different extraction methods.

Figure 3

SDS-PAGE experimental results of each protein extract. Lanes 1–4 are the extracts of leather samples aged 6, 12, 24, and 48 h, respectively. Lane M is the standard protein. Lane 5 is the extract of the micro-collection sample.

Figure 4

Full-scale scan of the first-class mass spectrum of the peptide VIDELDVKPEGTR.

Figure 5

MS/MS spectrum and the b and y fragments of the peptide sequence VIDELDVKPEGTR.