Using MALDI-FTICR mass spectrometry to enhance ZooMS identifications of
Pleistocene bone fragments showing variable collagen preservation
Abstract
Rationale Recent advances in high-throughput molecular analyses
of collagen peptides, especially ZooMS (Zooarchaeology by Mass
Spectrometry), have forced breakthroughs in the analysis of
archaeological material that is highly fragmented, a factor that hinders
morphological identification. Despite these advances, the challenge of
successfully analysing archaeological samples with poorer collagen
preservation persists. This paper examines the potential of two mass
analysers, TOF ( Time of Flight) and FTICR (
Fourier-transform ion cyclotron resonance), and addresses how
they can be used to optimise the ZooMS workflow. Methods Type 1
collagen (COL1) was extracted from 89 archaeological bones from the site
of Le Piage (37-34 ka cal BP) in France. Three ZooMS extraction
protocols were used, an acid-free buffer method (AmBic), offering rapid
and less destructive analysis, and two methods of acid demineralisation
(HCl and TFA) that provide higher peptide resolution. After analysing
the specimens with MALDI-TOF and MALDI-FTICR, we used bottom-up and PRM
( Parallel Reaction Monitoring) LC-MS/MS, and MALDI-CASI-FTICR (
Continuous Accumulation of Selected ions) to verify 26 less
secure identifications. Results Overall, 99 % of the samples
could be identified to at least family level, with the rate of
identification and precision varying by method. Despite challenges in
detecting specific biomarkers with MALDI-FTICR—especially peptide A
(COL1ɑ2 978–990), which tends to be unstable and poorly expressed—the
high resolution of this method allowed the successful identification of
more degraded specimens, including burnt bones. Conclusions Our
work highlights the robustness of traditional MALDI-TOF ZooMS for
retrieving collagen and for providing taxonomic identifications with low
failure rates, features that are critical when processing large numbers
of samples. MALDI-FTICR shows better potential for working with precious
samples or degraded collagen. Further, this study advances the
analytical detection of peptides by optimising the ZooMS workflow and by
tailoring it to specific archaeological contexts, which often show
variation in degree of preservation.