Detection of glycine as a model protein in blood serum using 2D-IR spectroscopy

Rutherford, Samantha H. and Greetham, Gregory M. and Donaldson, Paul M. and Towrie, Michael and Parker, Anthony W. and Baker, Matthew J. and Hunt, Neil T. (2021) Detection of glycine as a model protein in blood serum using 2D-IR spectroscopy. Analytical Chemistry, 93 (2). pp. 920-927. ISSN 0003-2700 (https://doi.org/10.1021/acs.analchem.0c03567)

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Abstract

Glycine (Gly) is used as a model system to evaluate the ability of ultrafast two-dimensional infrared (2D-IR) spectroscopy to detect and quantify the low-molecular-weight proteinaceous components of blood serum. Combining data acquisition schemes to suppress absorption bands of H2O that overlap with the protein amide I band with analysis of peak patterns appearing in the off-diagonal region of the 2D-IR spectrum allows separation of the Gly spectral signature from that of the dominant protein fraction of serum in a transmission-mode 2D-IR measurement without any sample manipulation, e.g., filtration or drying. 2D-IR spectra of blood serum samples supplemented with varying concentrations of Gly were obtained, and a range of data analysis methods compared, leading to a detection limit of ∼3 mg/mL for Gly. The reported methodology provides a platform for a critical assessment of the sensitivity of 2D-IR for measuring the concentrations of amino acids, peptides, and low-molecular-weight proteins present in serum samples. We conclude that, in the case of several clinically relevant diagnostic molecules and their combinations, the potential exists for 2D-IR to complement IR absorption methods as the benefits of the second frequency dimension offered by 2D-IR spectroscopy outweigh the added technical complexity of the measurement.

ORCID iDs

Rutherford, Samantha H., Greetham, Gregory M., Donaldson, Paul M., Towrie, Michael, Parker, Anthony W., Baker, Matthew J. ORCID logoORCID: https://orcid.org/0000-0003-2362-8581 and Hunt, Neil T. ORCID logoORCID: https://orcid.org/0000-0001-7400-5152;
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