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Patel VD, Shamsi SA, Miller A, Liu A. Quantitation of tryptophan and kynurenine in human plasma using 4-vinylphenylboronic acid column by capillary electrochromatography coupled with mass spectrometry. Electrophoresis 2023; 44:529-539. [PMID: 36718859 PMCID: PMC10129288 DOI: 10.1002/elps.202200251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 01/23/2023] [Accepted: 01/23/2023] [Indexed: 02/01/2023]
Abstract
Tryptophan (TRP) is an essential amino acid catabolized mainly through the kynurenine pathway, and part of it is catabolized in the brain. The abnormal depletion of TRP and production of kynurenine (KYN) by two enzymes, tryptophan 2,3-dioxygenase (TDO) and indoleamine 2,3-dioxygenase (IDO), have been linked to various neurological diseases. The ratio of TRP/KYN in plasma is a valuable measure for IDO/TDO activity and the prognosis of disease conditions. The 4-vinylphenylboronic acid (4-VPBA) was evaluated as a novel stationary phase for OT-CEC-MS/MS. TRP, KYN, and 3-hydroxykynurenine were separated using optimum conditions of 15 mM (NH4 )2 CO3 at pH 8 as a background electrolyte and 25 kV separation voltage on a 90 cm column. The usefulness of the 4-VPBA column for simple, fast, repeatable, and sensitive CEC-ESI-MS/MS application was demonstrated for the quantitation of TRP and KYN in the plasma of healthy human subjects and neuroinflammation subjects. The plasma sample was extracted on a zirconia-based ion-exchange cartridge for simultaneous protein precipitation and phospholipid removal. The method of standard addition, in combination with the internal standards approach, was used to prepare the calibration curve to overcome matrix matching and eliminate procedural errors. The developed quantitation method was validated according to FDA guidelines for sensitivity, accuracy, precision, and extraction recovery. The measured plasma level of TRP and KYN in healthy humans is aligned with the human metabolome database for the same two metabolites.
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Affiliation(s)
- Vijay D. Patel
- Department of Chemistry, Georgia State University, Atlanta, Georgia, USA
| | - Shahab A. Shamsi
- Department of Chemistry, Georgia State University, Atlanta, Georgia, USA
| | - Andrew Miller
- Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, Georgia, USA
| | - Aimin Liu
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, Texas, USA
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2
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Halvorsen TG, Reubsaet L. The utility of molecularly imprinted polymers for mass spectrometric protein and proteomics analysis. Proteomics 2022; 22:e2100395. [PMID: 36217925 DOI: 10.1002/pmic.202100395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 09/30/2022] [Accepted: 10/04/2022] [Indexed: 11/08/2022]
Abstract
Selective and efficient sample clean-up is important in mass spectrometric protein- and proteomics analyses from biological matrices. Molecularly imprinted polymers (MIPs), polymers prepared to have tailor-made cavities for capture of target analytes may by such represent an interesting alternative for selective clean-up. The present review aims to give an overview of the utility of MIPs for protein capture from biological matrices prior to mass spectrometry (MS) analysis. The application of MIPs in depletion of abundant proteins, in protein and proteotypic peptide capture as well as in capture of post-translational modifications (PTMs) is described and discussed. In addition, an overview of available MIP formats and their advantages and challenges is given, together with an overview of the mass spectrometric techniques used in protein analysis after MIP capture. Overall, the present literature demonstrates that for many applications MIPs for sample clean-up in mass spectrometric protein and proteomics analysis from biological matrices is still not fully matured. MIPs for proteotypic peptide capture is the most mature approach and a method for routine use may be available within the next few years.
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Affiliation(s)
| | - Léon Reubsaet
- Department of Pharmacy, University of Oslo, Oslo, Norway
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3
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Affinity capture in bottom-up protein analysis - Overview of current status of proteolytic peptide capture using antibodies and molecularly imprinted polymers. Anal Chim Acta 2021; 1182:338714. [PMID: 34602193 DOI: 10.1016/j.aca.2021.338714] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 05/27/2021] [Accepted: 05/28/2021] [Indexed: 12/17/2022]
Abstract
Antibody-based affinity capture has become the gold standard in sample preparation for determination of low-abundance protein biomarkers in biological matrices prior to liquid chromatography-mass spectrometry (LC-MS) determination. This comprises both capture of intact proteins prior to the digestion step and capture of proteolytic peptides after digestion of the sample. The latter can be performed both using antibodies specifically developed to capture target proteolytic peptides, as well as by the less explored use of anti-protein antibodies to capture the proteolytic epitope peptide. Molecularly imprinted polymers (MIPs), also called plastic antibodies are another affinity-based approach emerging as sample preparation technique in LC-MS based protein biomarker analysis. The current review gives a critical and comprehensive overview of proteolytic peptide capture using antibodies and MIPs in LC-MS based protein biomarker determination during the last five years. The main emphasis is on capture of non-modified peptides, while a brief overview of affinity capture of peptides containing post-translational modifications (PTMs) is provided.
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McKitterick N, Bicak TC, Switnicka-Plak MA, Cormack PAG, Reubsaet L, Halvorsen TG. On-line duplex molecularly imprinted solid-phase extraction for analysis of low-abundant biomarkers in human serum by liquid chromatography-tandem mass spectrometry. J Chromatogr A 2021; 1655:462490. [PMID: 34479097 DOI: 10.1016/j.chroma.2021.462490] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 08/18/2021] [Accepted: 08/20/2021] [Indexed: 12/01/2022]
Abstract
In the present work, a pair of molecularly imprinted polymers (MIPs) targeting distinct peptide targets were packed into trap columns and combined for automated duplex analysis of two low abundant small cell lung cancer biomarkers (neuron-specific enolase [NSE] and progastrin-releasing peptide [ProGRP]). Optimization of the on-line molecularly imprinted solid-phase extraction (MISPE) protocol ensured that the MIPs had the necessary affinity and selectivity towards their respective signature peptide targets - NLLGLIEAK (ProGRP) and ELPLYR (NSE) - in serum. Two duplex formats were evaluated: a physical mixture of the two MIPs (1:1 w/w ratio) inside a single trap column, and two separate MIP trap columns connected in series. Both duplex formats enabled the extraction of the peptides from serum. However, the trap columns in series gave superior extraction efficiency (85.8±3.8% and 49.1±6.7% for NLLGLIEAK and ELPLYR, respectively). The optimized protocol showed satisfactory intraday (RSD≤23.4 %) and interday (RSD≤14.6%) precision. Duplex analysis of NSE and ProGRP spiked into digested human serum was linear (R2≥0.98) over the disease range (0.3-30 nM). The estimated limit of detection (LOD) and limit of quantification (LOQ) were 0.11 nM and 0.37 nM, respectively, for NSE, and 0.06 nM and 0.2 nM, respectively, for ProGRP. Both biomarkers were determined at clinically relevant levels. To the best of our knowledge, the present work is the first report of an automated MIP duplex biomarker analysis. It represents a proof of concept for clinically viable duplex analysis of low abundant biomarkers present in human serum or other biofluids.
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Affiliation(s)
- Nicholas McKitterick
- Section for Pharmaceutical Chemistry, Department of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway
| | - Tugrul Cem Bicak
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow G1 1XL, Scotland, UK
| | - Magdalena A Switnicka-Plak
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow G1 1XL, Scotland, UK
| | - Peter A G Cormack
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow G1 1XL, Scotland, UK.
| | - Léon Reubsaet
- Section for Pharmaceutical Chemistry, Department of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway
| | - Trine Grønhaug Halvorsen
- Section for Pharmaceutical Chemistry, Department of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway.
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Abstract
Molecularly imprinted polymers (MIPs) are currently widely used and further developed for biological applications. The MIP synthesis procedure is a key process, and a wide variety of protocols exist. The templates that are used for imprinting vary from the smallest glycosylated glycan structures or even amino acids to whole proteins or bacteria. The low cost, quick preparation, stability and reproducibility have been highlighted as advantages of MIPs. The biological applications utilizing MIPs discussed here include enzyme-linked assays, sensors, in vivo applications, drug delivery, cancer diagnostics and more. Indeed, there are numerous examples of how MIPs can be used as recognition elements similar to natural antibodies.
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McKitterick N, Braathen F, Switnicka-Plak MA, Cormack PAG, Reubsaet L, Halvorsen TG. Magnetic Synthetic Receptors for Selective Clean-Up in Protein Biomarker Quantification. J Proteome Res 2020; 19:3573-3582. [PMID: 32614597 PMCID: PMC7467826 DOI: 10.1021/acs.jproteome.0c00258] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
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Biomarker analysis by mass spectrometry
(MS) can allow for the
rapid quantification of low abundant biomarkers. However, the complexity
of human serum is a limiting factor in MS-based bioanalysis; therefore,
novel biomarker enrichment strategies are of interest, particularly
if the enrichment strategies are of low cost and are easy to use.
One such strategy involves the use of molecularly imprinted polymers
(MIPs) as synthetic receptors for biomarker enrichment. In the present
study, a magnetic solid-phase extraction (mSPE) platform, based on
magnetic MIP (mMIP) sorbents, is disclosed, for use in the MS-based
quantification of proteins by the bottom-up approach. Progastrin releasing
peptide (ProGRP), a low abundant and clinically sensitive biomarker
for small cell lung cancer (SCLC), was used to exemplify the mSPE
platform. Four different mMIPs were synthesized, and an mSPE method
was developed and optimized for the extraction of low concentrations
of tryptic peptides from human serum. The mSPE method enabled the
selective extraction of the ProGRP signature peptide, the nonapeptide
NLLGLIEAK, prior to quantification of the target via LC-MS/MS. Overall,
the mSPE method demonstrated its potential as a low cost, rapid, and
straightforward sample preparation method, with demonstrably strong
binding, acceptable recoveries, and good compatibility with MS. mMIPs
are a potential low-cost alternative to current clinical methods for
biomarker analysis.
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Affiliation(s)
- Nicholas McKitterick
- Section for Pharmaceutical Chemistry, Department of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway
| | - Frida Braathen
- Section for Pharmaceutical Chemistry, Department of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway
| | - Magdalena A Switnicka-Plak
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow G1 1XL, Scotland, U.K
| | - Peter A G Cormack
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow G1 1XL, Scotland, U.K
| | - Léon Reubsaet
- Section for Pharmaceutical Chemistry, Department of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway
| | - Trine Grønhaug Halvorsen
- Section for Pharmaceutical Chemistry, Department of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway
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Boysen RI. Advances in the development of molecularly imprinted polymers for the separation and analysis of proteins with liquid chromatography. J Sep Sci 2018; 42:51-71. [PMID: 30411488 DOI: 10.1002/jssc.201800945] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 10/23/2018] [Accepted: 10/24/2018] [Indexed: 12/20/2022]
Abstract
This review documents recent advances in the design, synthesis, characterization, and application of molecularly imprinted polymers in the form of monoliths and particles/beads for the use in the separation and analysis of proteins with solid-phase extraction or liquid chromatography. The merits of three-dimensional molecular imprinting, whereby the molecular template is randomly embedded in the polymer, and two-dimensional imprinting, in which the template is confined to the surface, are described. Target protein binding can be achieved by either using the entire protein as a template or by using a protein substructure as template, that is, a peptide, as in the "epitope" approach. The intended approach and strategy then determine the choice of polymerization method. A synopsis has been provided on methods used for the physical, chemical, and functional characterizations and associated performance evaluations of molecularly imprinted and nonimprinted control polymers, involving a diverse range of analytical techniques commonly used for low and high molecular mass analytes. Examples of recent applications demonstrate that, due to the versatility of imprinting methods, molecularly imprinted monoliths or particles/beads can be adapted to protein extraction/depletion and separation procedures relevant to, for example, protein biomarker detection and quantification in biomedical diagnostics and targeted proteomics.
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Thomas A, Schänzer W, Thevis M. Immunoaffinity techniques coupled to mass spectrometry for the analysis of human peptide hormones: advances and applications. Expert Rev Proteomics 2017; 14:799-807. [PMID: 28758805 DOI: 10.1080/14789450.2017.1362338] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
INTRODUCTION The accurate and comprehensive determination of peptide hormones from biological fluids has represented a considerable challenge to analytical chemists for decades. Besides long-established bioanalytical ligand binding assays (or ELISA, RIA, etc.), more and more mass spectrometry-based methods have been developed recently for purposes commonly referred to as targeted proteomics. Eventually the combination of both, analyte extraction by immunoaffinity and subsequent detection by mass spectrometry, has shown to synergistically enhance the test methods' performance characteristics. Areas covered: The review provides an overview about the actual state of existing methods and applications concerning the analysis of endogenous peptide hormones. Here, special focus is on recent developments considering the extraction procedures with immobilized antibodies, the subsequent separation of target analytes, and their detection by mass spectrometry. Expert commentary: Key aspects of procedures aiming at the detection and/or quantification of peptidic analytes in biological matrices have experienced considerable improvements in the last decade, particularly in terms of the assays' sensitivity, the option of multiplexing target compounds, automatization, and high throughput operation. Despite these advances and progress as expected to be seen in the near future, immunoaffinity purification coupled to mass spectrometry is not yet a standard procedure in routine analysis compared to ELISA/RIA.
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Affiliation(s)
- Andreas Thomas
- a Institute of Biochemistry/Center for Preventive Doping Research , German Sport University Cologne , Cologne , Germany
| | - Wilhelm Schänzer
- a Institute of Biochemistry/Center for Preventive Doping Research , German Sport University Cologne , Cologne , Germany
| | - Mario Thevis
- a Institute of Biochemistry/Center for Preventive Doping Research , German Sport University Cologne , Cologne , Germany.,b European Monitoring Center for Emerging Doping Agents (EuMoCEDA) , Cologne/Bonn , Germany
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Rossetti C, Ore OG, Sellergren B, Halvorsen TG, Reubsaet L. Exploring the peptide retention mechanism in molecularly imprinted polymers. Anal Bioanal Chem 2017; 409:5631-5643. [PMID: 28752338 DOI: 10.1007/s00216-017-0520-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 07/09/2017] [Accepted: 07/12/2017] [Indexed: 12/18/2022]
Abstract
Molecularly imprinted polymers (MIPs) have been used as useful sorbents in solid-phase extraction for a wide range of molecules and sample matrices. Their unique selectivity can be fine-tuned in the imprinting process and is crucial for the extraction of macromolecules from complex matrices such as serum. A relevant example of this is the application of MIPs to peptides in diagnostic assays. In this article the selectivity of MIPs, previously implemented in a quantitative mass-spectrometric assay for the biomarker pro-gastrin-releasing peptide, is investigated. Partial least squares regression was used to generate models for the evaluation and prediction of the retention mechanism of MIPs. A hypothesis on interactions of MIPs with the target peptide was verified by ad hoc experiments considering the relevant peptide physicochemical properties highlighted from the multivariate analysis. Novel insights into and knowledge of the driving forces responsible for the MIP selectivity have been obtained and can be directly used for further optimization of MIP imprinting strategies. Graphical Abstract Applied analytical strategy: the Solid Phase Extraction (SPE) of digested Bovin Serum Albumin (BSA), using Molecularly Imprinted Polymers (MIP), is followed by the liquid chromatography-mass spectrometry (LC-MS) analysis for the identification of the retained peptides. The further application of multivariate analysis allows setting up a Partial Least Square (PLS) model, which describes the peptide retention into the MIP and gives additional knowledge to be used in the optimization of the MIP and the whole SPE method.
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Affiliation(s)
- Cecilia Rossetti
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of Oslo, P.O. Box 1068, Blindern, 0316, Oslo, Norway
| | - Odd Gøran Ore
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of Oslo, P.O. Box 1068, Blindern, 0316, Oslo, Norway
| | - Börje Sellergren
- Department of Biomedical Sciences, Faculty of Health and Society, University of Malmö, 20506, Malmö, Sweden
| | - Trine Grønhaug Halvorsen
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of Oslo, P.O. Box 1068, Blindern, 0316, Oslo, Norway
| | - Léon Reubsaet
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of Oslo, P.O. Box 1068, Blindern, 0316, Oslo, Norway.
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Levernæs MCS, Broughton MN, Reubsaet L, Halvorsen TG. To elute or not to elute in immunocapture bottom-up LC–MS. J Chromatogr B Analyt Technol Biomed Life Sci 2017; 1055-1056:51-60. [DOI: 10.1016/j.jchromb.2017.03.044] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 03/03/2017] [Accepted: 03/23/2017] [Indexed: 02/07/2023]
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