A method for automatic building of protein structures has been developed. The method is based on the concept of flexible structure units. A structure unit is a fragment (group) of about ten atoms that is positioned in the electron density by a phased rotation and translation function. The positions, orientations and internal torsion angles of all structure units are refined by a phased flexible refinement. Individual structure units are connected into polyalanine chains. The sequence is aligned by combined marker and rotamer methods. The side chains are built either by the marker method and a full conformational search or by the rotamer method. Side chains are independent structure units. The structure unit represents a generalized atom and the group model can be refined by the least-squares method. The protein model is built with an accuracy of about 0.2 A at resolutions of 1.2-1.9 A. Partial results can be obtained at resolutions of between 2.0 and 2.3 A.
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http://dx.doi.org/10.1107/S0907444904015252 | DOI Listing |
J Phys Chem Lett
January 2025
School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, Kerala 695551, India.
Electronic coupling between individual redox units in a molecular assembly dictates their charge transfer efficacy. Being a well-defined crystalline structure, the metal-organic framework (MOF) ensures proper positioning of redox-active moieties and provides a unique platform to unveil their charge transfer dynamics and quantification with structural relationships. Here, we demonstrate a novel redox-active MOF with near-infrared through-space intervalence charge transfer by introducing a mixed valence state inside redox-active thiazolothiazole-based ligands (DPTTZ) upon photo- or electrochemical reduction.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China.
Frustrated Lewis pair chemistry (FLP) occupy a crucial position in nonmetal-mediated catalysis, especially toward activation of inert gas molecules. Yet, one formidable issue of homogeneous FLP catalysts is their instability on preservation and recycling. Here we contribute a general solution that marries the polyhedral oligomeric silsesquioxane (POSS) with a structurally specific frustrated Lewis acid to fabricate porous polymer networks, which can form water-insensitive heterogeneous FLP catalysts upon employing Lewis base substrates.
View Article and Find Full Text PDFNutrients
January 2025
School of Medicine, Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, UK.
Background/objectives: Vitamin K-dependent proteins (VKDPs) all commonly possess specially modified γ-carboxyglutamic acid residues created in a vitamin K-dependent manner. Several liver-derived coagulation factors are well characterised VKDPs. However, much less is known about extrahepatic VKDPs, which are more diverse in their molecular structures and functions, and some of which have been implicated in inflammatory disorders.
View Article and Find Full Text PDFMolecules
January 2025
Organization for Marine Science and Technology, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
High-Density Polyethylene (HDPE) and Low-Density Polyethylene (LDPE) films were used to create nanoplastic (NP) models, with the shape of delamination occurring during degradation. In the case of HDPE, selective degradation occurred not only in the amorphous part, but also in the crystalline part at the same time. Some of the lamellae that extend radially to form the spherulite structure were missing during the 30-day degradation.
View Article and Find Full Text PDFInsects
December 2024
Department of Veterinary Medicine, College of Agriculture and Veterinary Medicine, United Arab Emirates University, Al-Ain P.O. Box 15551, United Arab Emirates.
ticks are the main hematophagous ectoparasites of camels, harboring a variety of microbes that can affect tick vector competence and pathogen transmission. To better understand the tick microbiome influenced by sex and host habitat, we analyzed the bacterial community of male and female ticks collected from camel farms, livestock markets, and slaughterhouses, representing the range of major habitats in the UAE, by sequencing the 16S rRNA gene. Tick samples were collected during 2022 and 2023.
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