Selective labeling of pulmonary surfactant protein SP-C in organic solution

Pulmonary surfactant protein SP-C has been isolated from porcine lungs and treated with dansyl isothiocyanate in chloroform: methanol 2:1 (v/v) soluti ons, under conditions optimized to introduce a single dansyl group covalent ly attached to the N-terminal amine group of the protein without loss of it s native thioesther-linked palmitic chains. The resulting derivative Dans-S P-C conserves the secondary structure of native SP-C as well as the ability to promote interfacial adsorption of DPPC suspensions and to affect the th ermotropic behavior of DPPC bilayers. This derivative can be used to charac terize lipid-protein and protein-protein interactions of a native-like SP-C in lipid/protein complexes. (C) 2001 Academic Press.