Designed β-hairpin peptides with defined tight turn stereochemistry

The conformational analysis of two synthetic octapeptides, Boc-Leu-Val-Val-D-Pro-L-Ala-Leu-Val-Val-OMe (1) and Boc-Leu-Val-Val-D-Pro-D-Ala-Leu-Val-Val-OMe (2) has been carried out in order to investigate the effect of β-turn stereochemistry on designed β-hairpin structures. Five hundred megahertz 1H NMR studies establish that both peptides 1 and 2 adopt predominantly β-hairpin conformations in methanol solution. Specific nuclear Overhauser effects provide evidence for a type II′ β-turn conformation for the D-Pro-L-Ala segment in 1, while the NMR data suggest that the type I D-Pro-D-Ala β-turn conformation predominates in peptide 2. Evidence for a minor conformation in peptide 2, in slow exchange on the NMR time scale, is also presented. Interstrand registry is demonstrated in both peptides 1 and 2. The crystal structure of 1 reveals two independent molecules in the crystallographic asymmetric unit, both of which adopt β-hairpin conformations nucleated by D-Pro-L-Ala type II′ β-turns and are stabilized by three cross-strand hydrogen bonds. CD spectra for peptides 1 and 2 show marked differences, presumably as a consequence of the superposition of spectral bands arising from both β-turn and β-strand conformations

Synthesis and characterization of dioxouranium (VI) complexes of schiff bases derived from isatin, isovanillin and <i>o</i>-vanillin

66-68Three schiff bases viz. isatin semicarbazone, isovanillin thiosemicarbazone, o-vanillin para-anisidineand their dioxouranium(VI) complexes have been synthesised and characterized by elemental analysis, IR and NMR spectral studies

De novo design of a five-stranded β-sheet anchoring a metal-ion binding site

A five-stranded β-sheet bearing two histidine residues as part of a metal-binding site has been designed, synthesised and characterised using NMR and electrospray ionization mass spectrometry techniques

Studies on arylfuran derivatives: Part IX-Synthesis and characterization of some fluorine containing arylfurylvinylquinazolinones as possible antibacterial agents

343-34

Folding of the C-terminal bacterial binding domain in statherin upon adsorption onto hydroxyapatite crystals

Statherin is an enamel pellicle protein that inhibits hydroxyapatite (HAP) nucleation and growth, lubricates the enamel surface, and is recognized by oral bacteria in periodontal diseases. We report here from solid-state NMR measurements that the protein's C-terminal region folds into an α-helix upon adsorption to HAP crystals. This region contains the binding sites for bacterial fimbriae that mediate bacterial cell adhesion to the surface of the tooth. The helical segment is shown through long-range distance measurements to fold back onto the intermediate region (residues Y16–P28) defining the global fold of the protein. Statherin, previously shown to be unstructured in solution, undergoes conformation selection on its substrate mineral surface. This surface-induced folding of statherin can be related to its functionality in inhibiting HAP crystal growth and can explain how oral pathogens selectively recognize HAP-bound statherin