Penicillin binding proteins (PBPs) catalyze essential steps in the biosynthesis of peptidoglycan, the main component of the bacterial cell wall. PBPs can harbor two catalytic domains, namely the glycosyltransferase (GT) and transpeptidase (TP) activities, the latter being the target for β-lactam antibiotics. Despite the availability of structural information regarding bi-functional PBPs, little is known regarding the interaction and flexibility between the TP and GT domains. Here, we describe the structural characterization in solution by small angle X-ray scattering (SAXS) of PBP1b, a bi-functional PBP from Streptococcus pneumoniae. The molecule is present in solution as an elongated monomer. Refinement of internal coordinates starting from a homology model yields models in which the two domains are in an extended conformation without any mutual contact compatible with the existence of restricted mobility.
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http://dx.doi.org/10.1016/j.bbrc.2011.01.003 | DOI Listing |
Adv Mater
December 2024
Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
Magnetoplumbites are one of the most broadly studied families of hexagonal ferrites, typically with high magnetic ordering temperatures, making them excellent candidates for permanent magnets. However, magnetic frustration is rarely observed in magnetoplumbites. Herein, the discovery, synthesis, and characterization of the first Mn-based magnetoplumbite, as well as the first magnetoplumbite involving pnictogens (Sb), ASbMnO (A = K or Rb) are reported.
View Article and Find Full Text PDFLangmuir
December 2024
Department of Chemistry, University of Washington, Seattle, Washington 98195, United States.
Circular dichroism (CD) spectroscopy has emerged as a potent tool for probing chiral small-molecule ligand exchange on natively achiral quantum dots (QDs). In this study, we report a novel approach to identifying QD-biomolecule interactions by inducing chirality in CdS QDs using thermoresponsive elastin-like polypeptides (ELPs) engineered with C-terminal cysteine residues. Our method is based on a versatile two-step ligand exchange process starting from monodisperse oleate-capped QDs in nonpolar media and proceeding through an easily accessed achiral glycine-capped QD intermediate.
View Article and Find Full Text PDF3 Biotech
January 2025
Department of Biology, Faculty of Sciences, Azarbaijan Shahid Madani University, Tabriz, Iran.
In this study, chitosan/curcumin (CS/Cur) and chitosan/papain (CS/Pa) nanoparticles were prepared and then characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), and differential light scattering (DLS). Subsequently, release rate, porosity, swelling, degradability, anti-inflammatory, antioxidant, antibacterial, and cell viability tests were conducted to investigate and compare the healing potential of the nanoparticles for various types of wounds. The results of FTIR, XRD, and DLS indicated that the nanoparticles were manufactured correctly with a hydrodynamic diameter of 429 nm (CS/Cur) and 460 nm (CS/Pa), and zeta potential of 4.
View Article and Find Full Text PDFFront Endocrinol (Lausanne)
December 2024
Department of Rheumatology and Clinical Immunology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt- Universität zu Berlin, Berlin, Germany.
Introduction: Diabetes mellitus (DM) is a chronic metabolic disorder that increases fragility fracture risk. Conventional DXA-based areal bone mineral density (aBMD) assessments often underestimate this risk. Cortical Backscatter (CortBS) ultrasound, a radiation-free technique, non-invasively analyzes cortical bone's viscoelastic and microstructural properties.
View Article and Find Full Text PDFJACS Au
December 2024
Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
It has become increasingly evident that the conformational distributions of intrinsically disordered proteins or regions are strongly dependent on their amino acid compositions and sequence. To facilitate a systematic investigation of these sequence-ensemble relationships, we selected a set of 16 naturally occurring intrinsically disordered regions of identical length but with large differences in amino acid composition, hydrophobicity, and charge patterning. We probed their conformational ensembles with single-molecule Förster resonance energy transfer (FRET), complemented by circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy as well as small-angle X-ray scattering (SAXS).
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