Collagen proteins exchange oxygen with demineralisation and gelatinisation reagents and also with atmospheric moisture

TY - JOUR

T1 - Collagen proteins exchange oxygen with demineralisation and gelatinisation reagents and also with atmospheric moisture

AU - von Holstein, Isabella

AU - Von Tersch, Matthew

AU - Coutu, Ashley N

AU - Penkman, Kirsty E H

AU - Makarewicz, Cheryl A

AU - Collins, Matthew J

N1 - This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details

PY - 2018/3/30

Y1 - 2018/3/30

N2 - Rationale: The oxygen (O) isotope composition of collagen proteins is a potential indicator of adult residential location, useful for provenancing in ecology, archaeology and forensics. In acidic solution, proteins can exchange O from carboxylic acid moieties with reagent O. This study investigated whether this exchange occurs during demineralisation and gelatinisation preparation of bone/ivory collagen. Methods: EDTA and HCl demineralisation or gelatinisation reagents were made up in waters with different δ18O values, and were used to extract collagen from four skeletal tissue samples. Aliquots of extracted collagen were exposed to two different atmospheric waters, at 120°C and ambient temperature, and subsequently dried in a vacuum oven at 40°C or by freeze drying. Sample δ18O values were measured by HT-EA pyrolysis/IRMS using a zero-blank autosampler. Results: Collagen samples exchanged O with both reagent waters and atmospheric water, which altered sample δ18O values. Exchange with reagent waters occurred in all extraction methods, but was greater at lower pH. Damage to the collagen samples during extraction increased O exchange. The nature of exchange of O with atmospheric water depended on the temperature of exposure: kinetic fractionation of O was identified at 120°C but not at ambient temperature. Exchange was difficult to quantify due to the high variability of δ18O values between experimental replicates. Conclusions: Studies of δ18O values in collagen proteins should avoid extraction methods using acidic solutions.

AB - Rationale: The oxygen (O) isotope composition of collagen proteins is a potential indicator of adult residential location, useful for provenancing in ecology, archaeology and forensics. In acidic solution, proteins can exchange O from carboxylic acid moieties with reagent O. This study investigated whether this exchange occurs during demineralisation and gelatinisation preparation of bone/ivory collagen. Methods: EDTA and HCl demineralisation or gelatinisation reagents were made up in waters with different δ18O values, and were used to extract collagen from four skeletal tissue samples. Aliquots of extracted collagen were exposed to two different atmospheric waters, at 120°C and ambient temperature, and subsequently dried in a vacuum oven at 40°C or by freeze drying. Sample δ18O values were measured by HT-EA pyrolysis/IRMS using a zero-blank autosampler. Results: Collagen samples exchanged O with both reagent waters and atmospheric water, which altered sample δ18O values. Exchange with reagent waters occurred in all extraction methods, but was greater at lower pH. Damage to the collagen samples during extraction increased O exchange. The nature of exchange of O with atmospheric water depended on the temperature of exposure: kinetic fractionation of O was identified at 120°C but not at ambient temperature. Exchange was difficult to quantify due to the high variability of δ18O values between experimental replicates. Conclusions: Studies of δ18O values in collagen proteins should avoid extraction methods using acidic solutions.

KW - Journal Article

UR - http://www.scopus.com/inward/record.url?scp=85045851136&partnerID=8YFLogxK

U2 - 10.1002/rcm.8064

DO - 10.1002/rcm.8064

M3 - Article

C2 - 29360219

SN - 0951-4198

VL - 32

SP - 523

EP - 534

JO - Rapid communications in mass spectrometry

JF - Rapid communications in mass spectrometry

IS - 6

ER -