title: Long range Trp-Trp interaction initiates the folding pathway of a pro-angiogenic β-hairpin peptide.
abstract: HPLW, a designed VEGF (Vascular Endothelium Growth Factor) receptor-binding peptide, assumes a well folded β-hairpin conformation in water and is able to induce angiogenesis in vivo. In this study, we investigated at atomic resolution the thermal folding/unfolding pathway of HPLW by means of an original multi-technique approach combining DSC, NMR, MD and mutagenesis analyses. In particular, careful NMR investigation of the single proton melting temperatures together with DSC analysis accurately delineate the peptide folding mechanism, which is corroborated by computational folding/unfolding simulations. The HPLW folding process consists of two main events, which are successive but do not superimpose. The first folding step initiates at 320 K upon the hydrophobic collapse of the Trp5 and Trp13 side-chains which stabilizes the concurrent β-turn formation, whose COi-HNi + 3 hydrogen bond (Asp10 → Arg7) appears particularly stable. At 316 K, once the β-turn is completely formed, the two β-strands pair, very likely starting by Trp5 and Trp13, which thus play a key role also in the final step of the β-hairpin folding. Overall, here we describe a multi-state hierarchical folding pathway of a highly structured β-hairpin, which can be classified as a broken-zipper mechanism.
authors.affiliation: Istituto di Biostrutture e Bioimmagini, C.N.R., via Mezzocannone 16, 80134, Napoli (Italy).
authors.forename: Donatella
authors.initials: D
authors.lastname: Diana
authors.affiliation: Istituto di Biostrutture e Bioimmagini, C.N.R., via Mezzocannone 16, 80134, Napoli (Italy).
authors.forename: Lucia
authors.initials: L
authors.lastname: De Rosa
authors.affiliation: Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Seconda Università degli Studi Napoli, via Vivaldi 43, 81100, Caserta (Italy).
authors.forename: Maddalena
authors.initials: M
authors.lastname: Palmieri
authors.affiliation: Istituto di Biostrutture e Bioimmagini, C.N.R., via Mezzocannone 16, 80134, Napoli (Italy).
authors.forename: Anna
authors.initials: A
authors.lastname: Russomanno
authors.affiliation: Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Seconda Università degli Studi Napoli, via Vivaldi 43, 81100, Caserta (Italy).
authors.forename: Luigi
authors.initials: L
authors.lastname: Russo
authors.affiliation: Dipartimento di Scienze Chimiche, Università degli Studi di Catania, viale A. Doria 6, 95125, Catania (Italy).
authors.forename: Carmelo
authors.initials: C
authors.lastname: La Rosa
authors.affiliation: Istituto di Biostrutture e Bioimmagini, C.N.R., Via Gaifami 18, 95126, Catania (Italy).
authors.forename: Danilo
authors.initials: D
authors.lastname: Milardi
authors.affiliation: Istituto di Chimica del Riconoscimento Molecolare, C.N.R., via Bianco 9, 20131, Milano (Italy).
authors.forename: Giorgio
authors.initials: G
authors.lastname: Colombo
authors.affiliation: Istituto di Biostrutture e Bioimmagini, C.N.R., via Mezzocannone 16, 80134, Napoli (Italy).
authors.forename: Luca D
authors.initials: LD
authors.lastname: D'Andrea
authors.affiliation: Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Seconda Università degli Studi Napoli, via Vivaldi 43, 81100, Caserta (Italy).
authors.forename: Roberto
authors.initials: R
authors.lastname: Fattorusso
mesh_terms: D000595:Amino Acid Sequence; D002152:Calorimetry, Differential Scanning; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D056004:Molecular Dynamics Simulation; D016296:Mutagenesis; D010455:Peptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017510:Protein Folding; D017433:Protein Structure, Secondary; D058767:Protein Unfolding; D013816:Thermodynamics; D044366:Transition Temperature; D014364:Tryptophan / Q000737:chemistry* / Q000378:metabolism
chemical_list: D010455:Peptides; D014364:Tryptophan