Carbohydrate polymers are the most abundant organic substances on earth. Their degrees of polymerization range from tens to thousands of units, yet polymerases generate the relevant lengths without the aid of a template. To gain insight into template-independent length control, we investigated how the mycobacterial galactofuranosyl-transferase GlfT2 mediates formation of the galactan, a polymer of galactofuranose residues that is an integral part of the cell wall. We show that isolated recombinant GlfT2 can catalyze the synthesis of polymers with degrees of polymerization that are commensurate with values observed in mycobacteria, indicating that length control by GlfT2 is intrinsic. Investigations using synthetic substrates reveal that GlfT2 is processive. The data indicate that GlfT2 controls length by using a substrate tether, which is distal from the site of elongation. The strength of interaction of that tether with the polymerase influences the length of the resultant polymer. Thus, our data identify a mechanism for length control by a template-independent polymerase.
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http://dx.doi.org/10.1073/pnas.0901407106 | DOI Listing |
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Laboratory of Immunogenetics and Tissue Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland.
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View Article and Find Full Text PDFPLoS One
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ICU, Shandong Provincial Hospital affiliated to Shandong First Medical University, Jinan, Shandong Province, China.
Introduction: Patients with cerebral hemorrhage often require a tracheal intubation to protect the airway and maintain oxygenation. Due to the use of analgesic and sedative drugs during endotracheal intubation and the opening of the glottis may easily cause aspiration pneumonia. Ceftriaxone is a semi-synthetic third-generation cephalosporin with strong antimicrobial activity against most gram-positive and gram-negative bacteria.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, USA.
This study investigates the impact of structural isomerism on the excited state lifetime and redox energetics of heteroleptic [Ir(ppy)2(bpy)]+ and homoleptic Ir(ppy)3 photoredox catalysts using ground-state and time-dependent density functional theory methods. While the ground- and excited-state reduction potentials differ only slightly among the isomers of these complexes, our findings reveal significant variations in the radiative and non-radiative decay rates of the reactivity-controlling triplet 3MLCT states of these closely related species. The observed differences in radiative decay rates could be traced back to variations in the transition dipole moment, vertical energy gaps, and spin-orbit coupling of the isomers.
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Department of Animal Science, Faculty of Agriculture, Ahi Evran University, Kırşehir, Türkiye.
Japanese quail () is a popular experimental animal model in scientific research. The present study investigated the effects of dietary multiple enzyme supplementation on growth performance, carcass characteristics, nutrient digestibility and small intestinal histomorphology in quails fed diets based on wheat and soya bean meal. A total number of 192 1-day-old quails were assigned to three treatments with 16 replicates in each and four quails replicate for 38 days.
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