P-Glycoprotein functions as an ATP-driven active efflux pump for many natural products and chemotherapeutic drugs. Hydrophobic peptides have been shown to block drug uptake by P-glycoprotein, indicating that they might be transport substrates. The present study examines the interaction of the synthetic peptide series NAc-LnY-amide with the multidrug transporter. Several peptides in this series ...

The incorporation of a reduced amide bond, psi(CH(2)NH), into peptide results in an increase in the net positive charge and the perturbation of alpha-helical structure. By using this characteristic of the reduced amide bond, we designed and synthesized novel pseudopeptides containing reduced amide bonds, which had a great selectivity between bacterial and mammalian cells. A structure-activity r...

Automated tritium-hydrogen exchange measurements have been made on the linear octapeptide Val(5)-angiotensin II amide. All six amide hydrogens of the peptide backbone are observable, and are resolved into three classes according to their exchange rates. The rate of exchange of the slowest class, t(1/2) of 300 min at 0 degrees C (pH 2.5), is compared with that of hydrogens that exchange abnormal...

The minimal structure in the heat-stable inhibitor protein of cAMP-dependent protein kinase required for a low nanomolar potency of inhibition is the peptide Thr6-Tyr-Ala-Asp-Phe-Ile-Ala-Ser-Gly-Arg-Thr-Gly-Arg-Arg-Asn-Ala-+ ++Ile22-NH2 (PKI-(6-22)-amide). While primary structural determinants for interaction with the protein kinase are distributed throughout the 17 residues of this peptide, we...

We demonstrate how multimode 2D IR spectroscopy of the protein amide I' and II' vibrations can be used to distinguish protein secondary structure. Polarization-dependent amide I'-II' 2D IR experiments on poly-l-lysine in the beta-sheet, alpha-helix, and random coil conformations show that a combination of amide I' and II' diagonal and cross peaks can effectively distinguish between secondary st...

Peptide-coated surfaces are widely employed in biomaterial design, but quantifiable correlation between surface composition and biological response is challenging due to, for example, instrumental limitations, a lack of suitable model or limitations quantitatively correlating data from different analytical techniques. Here, we first establish reference material that allows control over amino ac...

We study atomic models of the thermodynamics of the structural transition of peptides that form alpha-helices. The effect of sequence variation on alpha-helix formation for alanine-rich peptides, Ac-Ala21-methyl amide (A21) and Ac-A5 (AAARA)3A-methyl amide (Fs peptide), is investigated by atomic simulation studies of the thermodynamics of the helix-coil transition in explicit water. The simulat...

a new biological active hexapeptide of c-terminal of nocistatin, contains glu-gln-lys-gln-leu-gln sequence was synthesized according to solid phase peptide synthesis on the surface of 2-chloro tritylchloride resin and using fmoc-protected amino acids in the presence of tbtu (o-(benzotriazol-1-yl)-n,n,n',n'-tetramethyl uranium tetrafluoroborate) as a coupling reagent. then, amidation o...

We studied fibril formation in a family of peptides based on PHF6 (VQIVYK), a short peptide segment found in the microtubule binding region of tau protein. N-Acetylated peptides AcVYK-amide (AcVYK), AcIVYK-amide (AcPHF4), AcQIVYK-amide (AcPHF5), and AcV-QIVYK-amide (AcPHF6) rapidly formed straight filaments in the presence of 0.15 m NaCl, each composed of two laterally aligned protofilaments ap...