Number of Acidic Residues.

Chemical characteristics of fossil peptides. Dinosaur peptide sequences were obtained from the literature and their alpha chain location and amino acid positions on the human collagen model determined. The prevalence of acidic residues (bolded, underlined) in the peptides was lower than predicted for “average” peptides of comparable lengths from pepsinized human collagen [38], implying that regions of collagen with a less acidic nature were preferentially preserved in the fossils.

化石肽的化学特征。本研究的恐龙肽序列源自公开文献，并确定了其在人类胶原蛋白模型上的α链（alpha chain）定位与氨基酸位点。相较于来自经胃蛋白酶水解的人胶原蛋白的同等长度“典型”肽段的预测值，本研究肽段中酸性氨基酸残基（加粗并下划线标注）的丰度更低，这表明胶原蛋白中酸性较弱的区域在化石中得到了优先保存。