CLA, a natural, highly hydrophobic cyclic nonapeptide with sequence c(Pro(1)-Pro(2)-Phe(3)-Phe(4)-Leu(5)-Ile(6)-Ile(7)-Leu(8)-Val(9)-), isolated from linseed oil, was found to possess a strong immunosuppressive activity comparable, in low doses, with that of CsA, with a mechanism that depends on the inhibition of the interleukin-1 and interleukin-2 action. Structural analysis of CLA and its related compounds has underlined that the presence of the tetrapeptide Pro-Pro-Phe-Phe sequence, the Pro-Pro cis amide bond, and the 'edge-to-face' interaction are possible important features for the immunosuppressive activity of CLA. To evaluate the role and significance of 'edge-to-face' interaction in the process of molecular recognition by receptors, we have synthesised three linear precursors and three cyclic analogues of CLA, in which one or both Phe residues have been replaced by beta(3)Phe residues. A conformational analysis by NMR in CD(3)CN/H(2)O mixture has been carried out on the CLA analogue, in which Phe(3) has been replaced by a betaPhe, to study the influence of the mutation on the three-dimensional structure. All linear and cyclic CLA analogues containing betaPhe have been tested in the humoral and cellular immune response in vivo assays in mice. The peptide activities have been compared with CsA, as a reference drug.
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Nat Commun
January 2025
Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.
The mycobacterial ABC transporter IrtAB features an ABC exporter fold, yet it imports iron-charged siderophores called mycobactins. Here, we present extensive cryo-EM analyses and DEER measurements, revealing that IrtAB alternates between an inward-facing and an outward-occluded conformation, but does not sample an outward-facing conformation. When IrtAB is locked in its outward-occluded conformation in nanodiscs, mycobactin is bound in the middle of the lipid bilayer at a membrane-facing crevice opening at the heterodimeric interface.
View Article and Find Full Text PDFInt J Biol Macromol
January 2025
State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy, and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin 300350, People's Republic of China. Electronic address:
A heteropolysaccharide, designated JYP70-1, was extracted and purified from the fruits of Rosa laevigata, exhibiting a molecular weight of 1.90 × 10 g/mol. Structural analysis revealed that JYP70-1 was composed of eleven sugar residues, including α-l-Araf-(1→, →3)-α-l-Araf-(1→, →5)-α-l-Araf-(1→, →3,5)-α-l-Araf-(1→, →2,5)-α-l-Araf-(1→, →4)-α-d-Galp-(1→, →6)-β-d-Galp-(1→, →6)-α-d-Glcp-(1→, α-d-Glcp-(1→, →2)-α-d-Manp-(1→, and →3,6)-β-d-Manp-(1→.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
January 2025
School of Food Science and Technology, Jiangnan University, Wuxi, PR China.
This study investigates camel milk protein structural dynamics during digestion using Fourier Transform Infrared (FTIR) spectroscopy and Two-Dimensional Infrared (2D-IR) homo-correlation and hetero-correlation analysis. The synchronous 2DIR homo-correlation map reveals that NH bending and C-N stretching vibrations (amide II) are sensitive to digestion, indicating significant impacts on secondary structures. The asynchronous 2DIR homo-correlation indicates a stepwise process, where initial disruptions in NH interactions precede changes in CO stretching vibrations (amide I), highlighting the sequence of structural alterations during protein unfolding and degradation.
View Article and Find Full Text PDFMar Pollut Bull
January 2025
School of Resources and Environment, Nanchang University, Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, Nanchang 330031, Jiangxi, China.
The widespread use of perfluoro/polyfluoroalkyl compounds (PFACs) makes it inevitable for them to be released into and affect the environment, and the octanol-water partition coefficient (logK) is a key indicator for evaluating the environmental behavior of trace pollutants and their impact on the environment. However, the determination of logK using experimental means is often time-consuming and laborious, or even unattainable. Therefore, the logKow of 20 per/polyfluoroalkyl compounds obtained from the PubChem database was selected as the object of study, and the 41 chemical descriptors required for modeling were obtained by density-functional theory calculations, and it was found that only two molecular descriptors (A, V) were significantly correlated with the logK, with the correlation of the descriptor A being the was the strongest.
View Article and Find Full Text PDFBiochem Biophys Res Commun
January 2025
College of Animal Science and Technology, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, Guangxi University, Nanning, 530004, Guangxi, China. Electronic address:
Aptamers, a kind of short nucleotide sequences with high specificity and affinity with targets, have attracted extensive attention in recent years. Molecular docking method (MDM) is the most common method to explore the binding mode and recognition mechanism of aptamers and small molecules, which generally use the target to dock with the highest scoring tertiary structural model of the aptamer, and the highest scoring result is used as the predicted model. However, this prediction results may miss out the true interaction pattern due to the fact that aptamers are not completely rigid and the natural aptamers conformations are not in a single state.
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