title: Reversing the peptide sequence impacts on molecular surface behaviour.
abstract: The protein's primary structure has all the information for specific protein/peptide folding and, in many cases, can define specific amphiphilic regions along molecules that are important for interaction with membranes. In order to shed light on how peptide sequence is important for the surface properties of amphiphilic peptides, we designed three pairs of peptides with the following characteristics: (1) all molecules have the same hydrophobic residues; (2) the couples differ from each other in their hydrophilic amino acids: positively, negatively and non-charged; (3) each pair has the same residues (same global molecular hydrophobicity) but the primary structure is reversed in comparison to its partner (retro-isomer), giving a molecule with a hydrophilic N or C-terminus and a hydrophobic C or N-terminus. Using the Langmuir monolayer approach, we observed that sequence reversal has a central role in the lateral stability of peptide monolayers, in the ability of the molecules to partition into the air-water interface and in the rheological properties of peptide films, whereas the peptide's secondary structure, determined by ATR-FTIR, was the same for all peptides. Reversing the sequence also gives a differential way of peptide/lipid interaction when peptides are in the presence of POPC lipid bilayers. Our results show how sequence inversion confers a distinctive peptide surface behaviour and lipid interaction for molecules with a similar structure.
authors.affiliation: CIQUIBIC, CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina. Electronic address: ambroggioernesto@yahoo.com.
authors.forename: Ernesto E
authors.initials: EE
authors.lastname: Ambroggio
authors.affiliation: CIQUIBIC, CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
authors.forename: Benjamín
authors.initials: B
authors.lastname: Caruso
authors.affiliation: Instituto de Investigaciones en Físico-Química de Córdoba (INFIQC), CONICET, Departamento de Matemática y Física, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, Argentina.
authors.forename: Marcos A
authors.initials: MA
authors.lastname: Villarreal
authors.affiliation: Centre for Structural Biology and Bioinformatics, Laboratory for Structure and Function of Biological Membranes, Universit é Libre de Bruxelles, CP 206/02, Blvd. du Triomphe, B-1050 Brussels, Belgium.
authors.forename: Vincent
authors.initials: V
authors.lastname: Raussens
authors.affiliation: CIQUIBIC, CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
authors.forename: Gerardo D
authors.initials: GD
authors.lastname: Fidelio
mesh_terms: D000595:Amino Acid Sequence; D001692:Biological Transport; D057927:Hydrophobic and Hydrophilic Interactions; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D010539:Permeability; D010713:Phosphatidylcholines / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D055672:Static Electricity; D013329:Structure-Activity Relationship; D053835:Unilamellar Liposomes / Q000737:chemistry*
chemical_list: D010455:Peptides; D010713:Phosphatidylcholines; D053835:Unilamellar Liposomes; C028694:1-palmitoyl-2-oleoylphosphatidylcholine
keywords: Peptide Langmuir monolayer stability; Peptide Langmuir rheology monolayer; Peptide adsorption/penetration into interfaces; Peptide retro-isomers; Peptide/membrane interaction