Abstract

Whey proteins including β-Lactoglobulin, α-Lactalbumin, Immunoglobulin-G, Serum Albumin, Lactoferrin, and Lactoperoxidase each have unique biological properties spanning anti-bacterial, anti-fungal, and anti-viral activities as well as deliver essential nutrients to the human body. In the past decade, there has been a large focus on extracting these individual proteins for their use in foods and supplements. In order to best extract these proteins and prepare them properly in foods and supplements, an understanding of how they behave and denature in different environments is necessary. However, there is insufficient knowledge of their thermodynamic properties and potential interactions in varying conditions. Additionally, there are no time- and cost- efficient methods for quantifying these proteins in their properly folded configurations which impacts their functional properties. In this research, we use differential scanning calorimetry (DSC) to first elucidate the melting temperature and enthalpy of unfolding of each individual whey protein across a range of pH buffers. We found that the whey protein’s melting temperatures can change by up to 20°C and enthalpy values can change up to 77.5% across pH 3.8-9.2 buffers. In general, the whey proteins were most stable between pH 5.5-7 according to their thermal properties. We also found that each whey protein can be identified on a single DSC scan in a 5mM EDTA 0.1M MOPs buffer pH 6.6. Next, we developed a DSC method which can quantify the individual folded whey proteins down to 0.17mg/ml in purified samples as well as quantify β-Lactoglobulin in mixed samples with all 6 proteins. Finally, we used DSC along with known protein-protein interaction assays to confirm previously known whey protein-protein interactions such as β-Lactoglobulin and Lactoferrin and found that this interaction primarily occurs with holo-Lactoferrin. We also show for the first time that Lactoferrin and Lactoperoxidase interact with many of the whey proteins. Overall, we show that DSC is a useful tool for evaluating the thermal stability and folding of whey proteins. Additionally, we developed novel ways of using DSC to quantify whey proteins and identify whey protein-protein interactions.

Degree

PhD

College and Department

Life Sciences; Microbiology and Molecular Biology

Rights

https://lib.byu.edu/about/copyright/

Date Submitted

2025-10-23

Document Type

Dissertation

Keywords

whey proteins, thermal stability, native structure, differential scanning calorimetry, protein quantification, protein-protein interactions

Language

english

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Life Sciences Commons

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