Deacylated pulmonary surfactant protein SP-C transforms from alpha-helical to amyloid fibril structure via a pH-dependent mechanism: an infrared structural investigation.

Bovine pulmonary surfactant protein C (SP-C) is a hydrophobic, alpha-helical membrane-associated lipoprotein in which cysteines C4 and C5 are acylated with palmitoyl chains. Recently, it has been found that the alpha-helix form of SP-C is metastable, and under certain circumstances may transform from an alpha-helix to a beta-strand conformation that resembles amyloid fibrils. This transformation is accelerated when the protein is in its deacylated form (dSP-C).