biostudies-literatureWalther FJNIEHS NIH HHSNHLBI NIH HHSe485https://www.ebi.ac.uk/biostudies/studies/S-EPMC4106191biostudies-literatureUnknown2Background. Surfactant protein C (SP-C; 35 residues) in lungs has a cationic N-terminal domain with two cysteines covalently linked to palmitoyls and a C-terminal region enriched in Val, Leu and Ile. Native SP-C shows high surface activity, due to SP-C inserting in the bilayer with its cationic N-terminus binding to the polar headgroup and its hydrophobic C-terminus embedded as a tilted, transmembrane α-helix. The palmitoylcysteines in SP-C act as 'helical adjuvants' to maintain activity by overriding the β-sheet propensities of the native sequences. Objective. We studied SP-C peptides lacking palmitoyls, but containing glutamate and lysine at 4-residue intervals, to assess whether SP-C peptides with salt-bridges ("ion-locks") promote surface activity by mimicking the α-helix and membrane PeerJSurfactant protein C peptides with salt-bridges ("ion-locks") promote high surfactant activities by mimicking the α-helix and membrane topography of the native protein.PMC4106191R01 ES015330R01 HL092158R01 HL094641Walther FJHernandez-Juviel JMRuchala PWaring AJNotter RHWang ZGordon LMfalseSurfactant protein C peptides with salt-bridges ("ion-locks") promote high surfactant activities by mimicking the α-helix and membrane topography of the native protein.Background. Surfactant protein C (SP-C; 35 residues) in lungs has a cationic N-terminal domain with two cysteines covalently linked to palmitoyls and a C-terminal region enriched in Val, Leu and Ile. Native SP-C shows high surface activity, due to SP-C inserting in the bilayer with its cationic N-terminus binding to the polar headgroup and its hydrophobic C-terminus embedded as a tilted, transmembrane α-helix. The palmitoylcysteines in SP-C act as 'helical adjuvants' to maintain activity by overriding the β-sheet propensities of the native sequences. Objective. We studied SP-C peptides lacking palmitoyls, but containing glutamate and lysine at 4-residue intervals, to assess whether SP-C peptides with salt-bridges ("ion-locks") promote surface activity by mimicking the α-helix and membrane 2014-01-01T00:00:00Z20142025-04-18T15:06:12.053Z2019-03-27T01:32:31ZS-EPMC41061912508334810.7717/peerj.485