title: Critical segment of apocytochrome c for its insertion into membrane.
abstract: Apocytochrome c has a potent ability to insert spontaneously into membrane. To identify which sequences were critical for this insertion activity, a series of peptides N19, C8, C15 and C21, corresponding to sequences 1-19, 81-88, 74-88 and 68-88 of apocytochrome c, respectively, were synthesized and purified. Insertion ability into phospholipid monolayer, intrinsic fluorescence emission spectra, and the accessibility of peptide C21 to fluorescence quenchers: KI, acrylamide and HB showed that only segment 68-88 could insert into membrane, while other segments did not. CD spectra demonstrated that its interaction with liposomes containing negatively charged phospholipid could induce a partial alpha-helical conformation in peptide C21. It is interesting to note that a cooperation exists between segment 68-88 and 1-19 in the insertion of apocytochrome c and consequently translocation across membrane.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, The Chinese Academy of Sciences, Beijing, China.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Wang
authors.forename: Xuehai
authors.initials: X
authors.lastname: Han
authors.forename: Fuyu
authors.initials: F
authors.lastname: Yang
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D002645:Chickens; D045304:Cytochromes c / Q000737:chemistry / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000378:metabolism; D010449:Peptide Mapping; D017433:Protein Structure, Secondary; D021381:Protein Transport; D013057:Spectrum Analysis
chemical_list: D008081:Liposomes; D008565:Membrane Proteins; D010446:Peptide Fragments; D045304:Cytochromes c