title: Cholesterol modulates maculosin's orientation in model systems of biological membranes. Relevance towards putative molecular recognition.
abstract: Fluorescence techniques were used to study (1) the extent of insertion of the bioactive cyclic dipeptide cyclo(l-tyrosyl-l-prolyl), maculosin, in model systems of membranes of 1, 2-palmitoyl-sn-glycero-3-phosphatidyl choline (DPPC) or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl choline (POPC), (2) its in-depth location in those lipidic membranes, and (3) the influence of cholesterol on the dipeptides's location and orientation. Partition into lipidic bilayers is extensive, mainly for liquid crystalline phase membranes (K(p)=1.3x10(4)). Maculosin locates at the lipid head groups level regardless of the membrane system. Nevertheless, its orientation is lipid phase dependent. When maculosin was inserted in liquid crystalline phase bilayers, its phenolic ring was perpendicular to the membrane surface, whereas it changed orientation when inserted in gel phase membranes. Cholesterol was able to reverse the lipid phase influence on maculosin's orientation.
authors.affiliation: Centro de Química-Física Molecular, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: Sílvia C D N
authors.initials: SC
authors.lastname: Lopes
authors.forename: Aleksander
authors.initials: A
authors.lastname: Fedorov
authors.forename: Miguel A R B
authors.initials: MA
authors.lastname: Castanho
mesh_terms: D016880:Anisotropy; D002784:Cholesterol / Q000494:pharmacology*; D005454:Fluorescence Polarization; D008567:Membranes, Artificial; D010456:Peptides, Cyclic / Q000737:chemistry*; D010879:Piperazines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D008567:Membranes, Artificial; D010456:Peptides, Cyclic; D010879:Piperazines; C085319:maculosin; D002784:Cholesterol