title: Effect of methylene group insertions on the structural rigidity of Aib containing helices.
abstract: Nonprotein amino acids are being extensively used in the design of synthetic peptides to create new structure mimics. In this study we report the effect of methylene group insertions in a heptapeptide Boc-Ala1-Leu2-Aib3-Xxx4-Ala5-Leu6-Aib7-OMe which nicely folds into a mixed 310 -/α-helical structure when Xxx= Ala. Analogs of this peptide have been made and studied by replacing central Xxx4 residue with Glycine (α-residue), β-Alanine (β-Αla), γ-aminobutyric acid (Gaba), and ε-aminocaproic acid (ε-Aca). NMR and circular dichroism were used to study the solution structure of these peptides. Crystals of the peptides containing alanine, β-Αla, and Gaba reveal that increasing the number of central methylene (-CH2 -) groups introduces local perturbations even as the helical structure is retained.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India.
authors.forename: Anju
authors.initials: A
authors.lastname: Duley
authors.affiliation: NMR Research Centre, Indian Institute of Science, Bangalore-, 560012, India.
authors.forename: Vasantha
authors.initials: V
authors.lastname: Gowda
authors.affiliation: Institute of Bioinformatics and Applied Biotechnology, Biotech Park, Electronics City Phase I, Bengaluru, 560 100, India.
authors.forename: Anjali
authors.initials: A
authors.lastname: Ganjiwale
authors.affiliation: NMR Research Centre, Indian Institute of Science, Bangalore-, 560012, India.
authors.forename: Srinivasarao
authors.initials: S
authors.lastname: Raghothama
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India.
authors.forename: Gurunath
authors.initials: G
authors.lastname: Ramanathan
mesh_terms: D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D010455:Peptides
keywords: Aib containing helices; mixed 310-/α- helices; β-alanine (β-Αla); γ-aminobutyric acid (Gaba); ε-aminocaproic acid (ε-Aca)