BioArCh, Biology (S-Block), University of York, York YO10 5YW, UK.
Rapid Commun Mass Spectrom. 2012 Oct 15;26(19):2319-27. doi: 10.1002/rcm.6351.
Non-enzymatic deamidation accumulates in aging tissues in vivo and has been proposed to be potentially useful as a molecular clock. The process continues post mortem, and here we explore the increase in levels of deamidation in archaeological collagen, as measured during Zooarchaeology by Mass Spectrometry (ZooMS) analysis.
With the high sensitivity of current generation mass spectrometers, ZooMS provides a non-destructive and highly cost-effective method to characterise collagen peptides. Deamidation can be detected by mass spectrometry as a +0.984 Da mass shift; therefore, aside from its original purpose, peptide mass-fingerprinting for bone identification, ZooMS concurrently yields a 'thermal indicator' of the samples.
By analysis of conventional ZooMS spectra, we determined the deamidation rate for glutamine residues in 911 bone collagen samples from 50 sites, with ages varying from medieval to Palaeolithic. The degree of deamidation was compared to diagenetic parameters and nearby sequence properties.
The extent of deamidation was found to be influenced more by burial conditions and thermal age than, for example, chronological age, the extent of bioerosion or crystallinity. The method lends itself mostly to screening heterogenic deposits of bone to identify outliers.
非酶促脱酰胺作用在体内的衰老组织中积累，并被提议作为一种潜在有用的分子钟。该过程在死后仍会继续，在这里我们探讨了在考古胶原中脱酰胺水平的增加，这是通过质谱分析（ZooMS）在动物考古学中测量的。
当前代质谱仪具有很高的灵敏度，ZooMS 提供了一种非破坏性且极具成本效益的方法来表征胶原蛋白肽。脱酰胺作用可以通过质谱检测到+0.984 Da 的质量位移；因此，除了其原始目的，即用于骨骼鉴定的肽质量指纹图谱外，ZooMS 同时提供了样品的“热指示器”。
通过对常规 ZooMS 光谱的分析，我们确定了 50 个地点的 911 个骨骼胶原蛋白样本中谷氨酰胺残基的脱酰胺率，年龄从中世纪到旧石器时代不等。将脱酰胺程度与成岩参数和附近序列特性进行了比较。
脱酰胺的程度更多地受到埋藏条件和热年龄的影响，而不是例如，chronological age、生物侵蚀的程度或结晶度。该方法主要适用于筛选骨骼的异质沉积物，以识别异常值。
