Thesis advisor: Mary F. Roberts / Thesis advisor: Eranthie Weerapana / Peripheral proteins from mammals often exhibit multi-domain structures and require metal ions such as calcium as co-factors. This dissertation investigates two types of such proteins -- pulmonary collectins (surfactant proteins A and D) and phosphatidylinositol-specific phospholipase C (PLC) delta1 -- and their interactions with model membranes. One approach to work around the complexity brought upon by such multi-domain protein structure is to use a truncated construct or an isolated single domain. For pulmonary collectins, homotrimers consisting of the neck domain and the carbohydrate recognition domain were used in a novel NMR assay for better understanding of their lipid-specific interactions with the membranes. For PLC delta1, we were particularly interested in the role of the EF-hand domain. The isolated EF-hand domain of PLC delta1 was first used to characterize its interactions with membranes and identify key residues responsible for such interactions. These key residues in the N terminal lobe of the EF-hand domain, either cationic or hydrophobic, were then found to affect the hydrolysis activity of the full-length enzyme. A common role for this region of the PLC in facilitating proper membrane association was thus proposed. / Thesis (PhD) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.