A custom fluorescence microscope for the observation of surface morphology at the air-water interface and an investigation of surface association and structure of deacylated surfactant protein C

by 1977- Leapard, James Brian

Surfactant Protein C (SP-C) is one of the two biophysically active proteins in pulmonary surfactant. Bovine SP-C (used in experiments in this thesis) consists of 34 amino acids and is an extremely hydrophobic, predominately ?-helical protein of approximately 4.0 kD. Cysteines C4 and C5 are acylated with C-16 (palmitoyl) chains via a thioester linkage. The NMR structure in apolar solvent describes the valine-, leucine- and isoleucine-rich region of this small protein as a rigid rod in which only a few residues near the N terminus (L1 – P7) and the C terminus itself are not helical. It has been recently shown that deacylation causes changes in the structure of the protein and accelerates the formation of amyloid fibrils. Experiments detailed in this thesis show that the deacylated protein is progressively excluded from the monolayer and that the secondary structure changes via a pH dependent mechanism.