Modeling deamidation in sheep α-keratin peptides and application to archaeological wool textiles

Caroline Solazzo; Julie Wilson; Jolon M Dyer; Stefan Clerens; Jeffrey Ernest Plowman; Isabella von Holstein; Penelope Walton Rogers; Elizabeth E Peacock; Matthew J Collins

doi:10.1021/ac4026362

Modeling deamidation in sheep α-keratin peptides and application to archaeological wool textiles

Caroline Solazzo, Julie Wilson, Jolon M Dyer, Stefan Clerens, Jeffrey Ernest Plowman, Isabella von Holstein, Penelope Walton Rogers, Elizabeth E Peacock, Matthew J Collins

Research output: Contribution to journal › Article › peer-review

Abstract

Deamidation of glutamine (Q) and asparagine (N) has been recognized as a marker of degradation and aging in ancient proteins. Using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-ToF-MS) to study deamidation in wool textiles, we identified eight peptides from α-keratin proteins in sheep wool that could potentially be used to assess the level of degradation. For each chosen peptide, the extent of deamidation was determined by comparing the calculated theoretical distribution with the measured distribution using a genetic algorithm that gives the best fit to the measured distribution. Variations in the levels of deamidation were observed between peptides and in modern wool samples buried for up to 8 years in which deamidation levels were relatively low under short-term burial. In contrast, deamidation was higher in archaeological textile fragments from medieval sites ranging from the 9th to 13th c. in York (UK) and Newcastle (UK) and from the 13th to 16th c. in Reykholt (Iceland). Major differences were observed between the British and the Icelandic samples, showing a negative correlation between age of samples and levels of deamidation, but highlighting the effect of local environment. In addition, nanoLC-ESI-MS/MS data indicated that deamidation in wool's α-keratin was influenced by primary and higher-order structures. Predominance of deamidation on glutamine rather than asparagine in the archaeological samples was attributed to a higher abundance of Q in the alpha-helical core domain of keratins, neighboring residues and steric hindrance preventing deamidation of N.

Original language	English
Pages (from-to)	567-575
Journal	Analytical Chemistry
Volume	86
Issue number	1
DOIs	https://doi.org/10.1021/ac4026362
Publication status	Published - 3 Dec 2013

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10.1021/ac4026362

http://pubs.acs.org/doi/abs/10.1021/ac4026362

Cite this

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title = "Modeling deamidation in sheep α-keratin peptides and application to archaeological wool textiles",

abstract = "Deamidation of glutamine (Q) and asparagine (N) has been recognized as a marker of degradation and aging in ancient proteins. Using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-ToF-MS) to study deamidation in wool textiles, we identified eight peptides from α-keratin proteins in sheep wool that could potentially be used to assess the level of degradation. For each chosen peptide, the extent of deamidation was determined by comparing the calculated theoretical distribution with the measured distribution using a genetic algorithm that gives the best fit to the measured distribution. Variations in the levels of deamidation were observed between peptides and in modern wool samples buried for up to 8 years in which deamidation levels were relatively low under short-term burial. In contrast, deamidation was higher in archaeological textile fragments from medieval sites ranging from the 9th to 13th c. in York (UK) and Newcastle (UK) and from the 13th to 16th c. in Reykholt (Iceland). Major differences were observed between the British and the Icelandic samples, showing a negative correlation between age of samples and levels of deamidation, but highlighting the effect of local environment. In addition, nanoLC-ESI-MS/MS data indicated that deamidation in wool's α-keratin was influenced by primary and higher-order structures. Predominance of deamidation on glutamine rather than asparagine in the archaeological samples was attributed to a higher abundance of Q in the alpha-helical core domain of keratins, neighboring residues and steric hindrance preventing deamidation of N.",

author = "Caroline Solazzo and Julie Wilson and Dyer, {Jolon M} and Stefan Clerens and Plowman, {Jeffrey Ernest} and {von Holstein}, Isabella and {Walton Rogers}, Penelope and Peacock, {Elizabeth E} and Collins, {Matthew J}",

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T1 - Modeling deamidation in sheep α-keratin peptides and application to archaeological wool textiles

AU - Solazzo, Caroline

AU - Wilson, Julie

AU - Dyer, Jolon M

AU - Clerens, Stefan

AU - Plowman, Jeffrey Ernest

AU - von Holstein, Isabella

AU - Walton Rogers, Penelope

AU - Peacock, Elizabeth E

AU - Collins, Matthew J

PY - 2013/12/3

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N2 - Deamidation of glutamine (Q) and asparagine (N) has been recognized as a marker of degradation and aging in ancient proteins. Using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-ToF-MS) to study deamidation in wool textiles, we identified eight peptides from α-keratin proteins in sheep wool that could potentially be used to assess the level of degradation. For each chosen peptide, the extent of deamidation was determined by comparing the calculated theoretical distribution with the measured distribution using a genetic algorithm that gives the best fit to the measured distribution. Variations in the levels of deamidation were observed between peptides and in modern wool samples buried for up to 8 years in which deamidation levels were relatively low under short-term burial. In contrast, deamidation was higher in archaeological textile fragments from medieval sites ranging from the 9th to 13th c. in York (UK) and Newcastle (UK) and from the 13th to 16th c. in Reykholt (Iceland). Major differences were observed between the British and the Icelandic samples, showing a negative correlation between age of samples and levels of deamidation, but highlighting the effect of local environment. In addition, nanoLC-ESI-MS/MS data indicated that deamidation in wool's α-keratin was influenced by primary and higher-order structures. Predominance of deamidation on glutamine rather than asparagine in the archaeological samples was attributed to a higher abundance of Q in the alpha-helical core domain of keratins, neighboring residues and steric hindrance preventing deamidation of N.

AB - Deamidation of glutamine (Q) and asparagine (N) has been recognized as a marker of degradation and aging in ancient proteins. Using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-ToF-MS) to study deamidation in wool textiles, we identified eight peptides from α-keratin proteins in sheep wool that could potentially be used to assess the level of degradation. For each chosen peptide, the extent of deamidation was determined by comparing the calculated theoretical distribution with the measured distribution using a genetic algorithm that gives the best fit to the measured distribution. Variations in the levels of deamidation were observed between peptides and in modern wool samples buried for up to 8 years in which deamidation levels were relatively low under short-term burial. In contrast, deamidation was higher in archaeological textile fragments from medieval sites ranging from the 9th to 13th c. in York (UK) and Newcastle (UK) and from the 13th to 16th c. in Reykholt (Iceland). Major differences were observed between the British and the Icelandic samples, showing a negative correlation between age of samples and levels of deamidation, but highlighting the effect of local environment. In addition, nanoLC-ESI-MS/MS data indicated that deamidation in wool's α-keratin was influenced by primary and higher-order structures. Predominance of deamidation on glutamine rather than asparagine in the archaeological samples was attributed to a higher abundance of Q in the alpha-helical core domain of keratins, neighboring residues and steric hindrance preventing deamidation of N.

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