Protein adducts as measures of exposure in epidemiological research

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  • March 21, 2019
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  • Funk, William Edward
    • Affiliation: Gillings School of Global Public Health, Department of Environmental Sciences and Engineering
Abstract
  • Protein adducts can serve as biomarkers of exposure to variety of xenobiotic toxicants and reactive endogenous species. However, despite their utility as exposure biomarkers, protein adducts have rarely been used in epidemiology. One reason for this is the cost and difficulty of obtaining blood samples, which frequently limits the uses of protein adducts as measures of exposure in large-scale studies. In addition, protein adducts are typically low in abundance compared with unmodified proteins, and are thus often difficult to detect in human blood. This research developed two novel methods that address these limitations in current assays of blood-protein adducts. First, to make blood proteins more accessible to epidemiologic studies, a method was developed to measure protein adducts in dried blood spots (DBS). Because DBS are easier to collect and store than conventional venous blood samples, they encourage applications of biomarkers of exposure in population studies. In addition, neonatal DBS which are collected from virtually all live births in the U.S. can be used to investigate chemical exposures in utero. Second, to increase analytical sensitivity for detecting less-abundant adducts, a method was developed to enrich cysteinyl adducts of human serum albumin (HSA). Because the major site of adduction of HSA is the single free sulfhydryl group located at Cys34, the enrichment approach utilized the propensity of mercaptalbumin (i.e., unadducted HSA) to bind with thiol-affinity resins. Furthermore, because the most common adducts of HSA-Cys34 are mixed disulfides formed by reversible reactions between Cys34 and serum thiols (notably cysteine), mixed disulfides were liberated via reduction with dithiothreitol (DTT) prior to removing mercaptalbumin with thiol affinity resins. These two methods provide a straightforward approach for obtaining and processing blood specimens so as to promote the use of protein adducts as biomarkers of exposure in epidemiologic investigations.
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  • In Copyright
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  • "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Environmental Sciences and Engineering, Gillings School of Global Public Health."
Advisor
  • Rappaport, Stephen Morris
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  • Chapel Hill, NC
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  • Open access
Date uploaded
  • March 18, 2013

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