| This thesis is an investigation of the interaction of vitamin D3 with beta-lactoglobulin and beta-casein using fluorimetry, circular dichroism, and atomic force microscopy. It is of nutritional significance to fortify dairy products (e.g. cheese, yogurt and ice cream) with vitamin D3; however, the inherent complexity of these foods may influence the stability and bioavailability of this nutrient. Hence, the objective of this research was to characterize the protein-vitamin interactions in environments of different pHs and ionic strengths. Results indicated that vitamin D 3 was bound to both beta-Lg and beta-CN. Depending on the solution conditions, beta-Lg K'd ranged between 0.02--0.29 muM, whereas beta-CN K'd ranged between 0.06--0.26 muM. Apparent molar ratios were also comparable, where 0.51--2.04 and 1.16--2.05 moles of vitamin D were bound per mole of beta-Lg and beta-CN, respectively. It was concluded that these interactions could help maintain vitamin D 3 stability and influence bioavailability. |
