title: Site-specific deamidation of glutamine: a new marker of bone collagen deterioration.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: BioArCh, Biology (S-Block), University of York, York YO10 5YW, UK. nienke@palaeo.eu
authors.forename: Nienke L
authors.initials: NL
authors.lastname: van Doorn
authors.forename: Julie
authors.initials: J
authors.lastname: Wilson
authors.forename: Hege
authors.initials: H
authors.lastname: Hollund
authors.forename: Marie
authors.initials: M
authors.lastname: Soressi
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Collins
mesh_terms: D000375:Aging / Q000378:metabolism*; D000577:Amides / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001106:Archaeology / Q000379:methods; D015415:Biomarkers / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D024042:Collagen Type I / Q000737:chemistry* / Q000378:metabolism*; D005060:Europe; D005973:Glutamine / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D000577:Amides; D015415:Biomarkers; D024042:Collagen Type I; D005973:Glutamine