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The jet-cooled spontaneous Raman spectrum of an amino acid-alanine (Ala, 2-aminopropanoic acid; H(2)NCH(CH(3))COOH)-is reported. The low-frequency vibrational spectrum (below 500 cm(-1)) was recorded and assigned using quantum chemical data: ab initio (MP2) and DFT (BLYP, B3LYP, and PBE0). Band polarization measurements were used to confirm the vibrational assignments. The acquired medium resolution spectra (HWHM of approximately 4 cm(-1)) allow the different alanine conformations to be distinguished. Four alanine conformers were observed and identified: two previously reported by microwave spectroscopy studies and two that were previously unreported. A set of reasons for why these conformers eluded previous studies are discussed. Selective collisional relaxation processes in the jet (associated with low interconversion barriers between different alanine conformations) that depopulate the high-energy conformers were experimentally demonstrated.
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http://dx.doi.org/10.1039/b924029b | DOI Listing |
J Alzheimers Dis
September 2025
Department of Neurology, Baylor College of Medicine, Houston, TX, USA.
BackgroundTau aggregation and propagation are hallmark features of Alzheimer's disease and related tauopathies. The molecular identity and post-translational modifications that contribute to tau seeding activity remain incompletely understood.ObjectiveTo characterize the temporal dynamics of tau seeding activity and identify specific phosphorylated tau species associated with tau propagation in vivo.
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Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States.
Complex coacervation has emerged as a powerful model for studying the self-assembly of intrinsically disordered proteins (IDPs) in biological condensates in cells. We characterized the phase behavior and rheology of coacervates formed from peptides with regular repeating sequences to examine the effects of charge patterning and hydrophobicity on coacervate stability and material properties. Our results show that increasing the size of charged blocks enhances salt resistance via electrostatic cooperativity, while incorporating small hydrophobic segments further stabilizes coacervates and increases viscosity through hydrophobic clustering.
View Article and Find Full Text PDFBiomolecules
July 2025
Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830017, China.
Sepsis is a fetal disease that requires a clear diagnostic biomarker for timely antibiotic treatment. Recent research has identified a pyroptosis-inducing epitope known as P5-5 in tetranectin (TN), a plasma protein produced by monocytes. Previously, we produced a 12F1 monoclonal antibody against the P5-5 and discovered that it could not only diagnose the presence but also monitor the progress of sepsis in the clinic.
View Article and Find Full Text PDFJ Phys Chem B
August 2025
Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States.
Developing accurate force fields for biomolecules remains a significant challenge due to the subtle energetic differences between various conformational states. We present a novel force field model for polyalanine, ALAMP2_25, developed using adaptive force matching (AFM) with Møller-Plesset perturbation theory at the second order (MP2) as the reference method. By fitting smaller model compounds and transferring parameters to larger peptides, we overcome the limitations of traditional AFM approaches and enable the use of more accurate electronic structure methods.
View Article and Find Full Text PDFSci Rep
August 2025
Department of Pharmacology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt.
Liver injury is a globally serious problem that may be observed post-chemotherapeutic administration in chronic crises such as tuberculosis (TB). Rifamycin (RIF), particularly, is an indispensable treatment regimen for TB with a significant negative hepatic impact. Therefore, this research aims to assess the restorative role of melatonin (MEL) against rifampicin (RIF)-associated hepatic damage in rats.
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