Thioxopeptide bond psi[CS-N], a nearly isosteric modification of the native peptide bond, was introduced into insect kinin active core pentapeptide to evaluate the impact of backbone cis/trans photoswitching on bioactivity. The thioxo analog Phe(1)-Tyr(2)-psi[CS-N]-Pro(3)-Trp(4)-Gly(5)-NH(2) (psi[CS-N](2)-kinin), was synthesized by Fmoc solid-phase peptide strategy. The reversible photoswitching property was characterized via spectroscopic methods and HPLC, which showed that the cis conformer increased from 15.7 to 47.7% after 254 nm UV irradiation. A slow thermal reisomerization (t(1/2) = 40 min) permitted us to determine the cockroach hindgut myotropic activity of the thioxopeptide in the photostationary state. The results indicated that the activity increased significantly after UV irradiation and recovered to the ground level after thermal re-equilibration. In the present study, by utilizing the phototriggered isomerization in a specific position of peptide backbone, we revealed that the cis psi[CS-N](2)-kinin conformer is the active conformation when interacting with kinin receptor on cockroach hindgut.

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At every turn: Electron paramagnetic resonance spectroscopy was used to investigate the dynamics of triple helix folding/unfolding of host–guest collagen mimetic peptide with a spin‐labeled central triplet in Ac‐(Gly‐Pro‐Hyp)7‐Gly‐Gly‐NH2 (see figure).

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This paper presents a novel approach to recognize images based on nonlinear wavelet approximation. The mathematical theory on nonlinear wavelet approximation is introduced, which shows that nonlinear approximation contains much more information of the original image than linear approximation. Based on this theory, a scheme to obtain the basic information of images with less data is provided. Experiments on face recognition produce effective matching rates.