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991.
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993.
Amit Sundriyal Claudia Massa Dietrich Samoray Fabian Zehender Timothy Sharpe Urs Jenal Tilman Schirmer 《The Journal of biological chemistry》2014,289(10):6978-6990
The universal second messenger cyclic di-GMP (cdG) is involved in the regulation of a diverse range of cellular processes in bacteria. The intracellular concentration of the dinucleotide is determined by the opposing actions of diguanylate cyclases and cdG-specific phosphodiesterases (PDEs). Whereas most PDEs have accessory domains that are involved in the regulation of their activity, the regulatory mechanism of this class of enzymes has remained unclear. Here, we use biophysical and functional analyses to show that the isolated EAL domain of a PDE from Escherichia coli (YahA) is in a fast thermodynamic monomer-dimer equilibrium, and that the domain is active only in its dimeric state. Furthermore, our data indicate thermodynamic coupling between substrate binding and EAL dimerization with the dimerization affinity being increased about 100-fold upon substrate binding. Crystal structures of the YahA-EAL domain determined under various conditions (apo, Mg2+, cdG·Ca2+ complex) confirm structural coupling between the dimer interface and the catalytic center. The built-in regulatory properties of the EAL domain probably facilitate its modular, functional combination with the diverse repertoire of accessory domains. 相似文献
994.
Amit Roy Natalia Solodovnikova Tracy Nicholson William Antholine William E Walden 《The EMBO journal》2004,23(24):4878
Addendum to: The EMBO Journal (2003) 22, 4826–4835. doi:10.1093/emboj/cdg455 相似文献
995.
Rosemary Tomichan Avinash Sharma K. Akash Adeeb Ahmad Siddiqui Amit Dubey Tarun Kumar Upadhyay Deepak Kumar Sadanand Pandey Rupak Nagraik 《Luminescence》2023,38(7):1102-1110
The review discusses the diagnostic application of biosensors as point-of-care devices in the COVID-19 pandemic. Biosensors are important analytical tools that can be used for the robust and effective detection of infectious diseases in real-time. In this current scenario, the utilization of smart, efficient biosensors for COVID-19 detection is increasing and we have included a few smart biosensors such as smart and intelligent based biosensors, plasmonic biosensors, field effect transistor (FET) biosensors, smart optical biosensors, surface enhanced Raman scattering (SERS) biosensor, screen printed electrode (SPE)-based biosensor, molecular imprinted polymer (MIP)-based biosensor, MXene-based biosensor and metal–organic frame smart sensor. Their significance as well as the benefits and drawbacks of each kind of smart sensor are mentioned in depth. Furthermore, we have compiled a list of various biosensors which have been developed across the globe for COVID-19 and have shown promise as commercial detection devices. Significant challenges in the development of effective diagnostic methods are discussed and recommendations have been made for better diagnostic outcomes to manage the ongoing pandemic effectively. 相似文献
996.
Rajesh Lokesh K. Gangwar Sujeet K. Mishra Amit Choudhary Ashok M. Biradar Gajjala Sumana 《Luminescence》2023,38(7):811-833
The application of liquid crystal (LC) materials has undergone a modern-day renaissance from its classical use in electronics industry as display devices to new-fangled techniques for optically detecting biological and chemical analytes. This review article deals with the emergence of LC materials as invaluable material for their use as label-free sensing elements in the development of optical, electro-optical and electrochemical biosensors. The property of LC molecules to change their orientation on perturbation by any external stimuli or on interaction with bioanalytes or chemical species has been utilized by many researches for the fabrication of high sensitive LC-biosensors. In this review article we categorized LC-biosensor based on biomolecular reaction mechanism viz. enzymatic, nucleotides and immunoreaction in conjunction with operating principle at different LC interface namely LC-solid, LC-aqueous and LC-droplets. Based on bimolecular reaction mechanism, the application of LC has been delineated with recent progress made in designing of LC-interface for the detection of bio and chemical analytes of proteins, virus, bacteria, clinically relevant compounds, heavy metal ions and environmental pollutants. The review briefly describes the experimental set-ups, sensitivity, specificity, limit of detection and linear range of various viable and conspicuous LC-based biosensor platforms with associated advantages and disadvantages therein. 相似文献
997.
998.
Circular permutation of betaB2-crystallin changes the hierarchy of domain assembly. 总被引:1,自引:0,他引:1 下载免费PDF全文
G. Wright A. K. Basak K. Wieligmann E. M. Mayr C. Slingsby 《Protein science : a publication of the Protein Society》1998,7(6):1280-1285
The betagamma-crystallins form a superfamily of eye lens proteins comprised of multiple Greek motifs that are symmetrically organized into domains and higher assemblies. In the betaB2-crystallin dimer each polypeptide folds into two similar domains that are related to monomeric gamma-crystallin by domain swapping. The crystal structure of the circularly permuted two-domain betaB2 polypeptide shows that permutation converts intermolecular domain pairing into intramolecular pairing. However, the dimeric permuted protein is, in fact, half a native tetramer. This result shows how the sequential order of domains in multi-domain proteins can affect quaternary domain assembly. 相似文献
999.
Purified hemicellulose isolated from a young bael (Aegle marmelos) tree with 2.5m sodium hydroxide contained d-xylose and 4-O-methyl-d-glucoronic acid in the molar ratio of 7.43:1; traces of glucose, galactose, rhamnose, and arabinose were also present. The linkages between the monosaccharide units were determined by methylation analysis of a hemicellulose fraction (II A) and carboxyl-reduced, hemicellulose II A, and the results were corroborated by those from periodate oxidation and Smith degradation. The anomeric configurations of the d-xylopyranosyl residues were determined by chromium(VI) trioxide oxidation of the acetylated, carboxyl-reduced hemicellulose, and the aldobiouronic acid obtained from graded hydrolysis was characterized. These experiments clearly revealed the structure of this hemicellulose. 相似文献
1000.
Summary The effect of phosphorus and molybdenum alone and combined, on the uptake and utilization of Mo, Mn, Zn, Cu and P by rice
(Var. IR-579) was studied in the greenhouse at varying levels of Mo (0, 2.5 and 5.0 ppm) and (0,100 and 200 ppm). Application
of P increased the dry matter yield of shoot and root. Combined application of P and Mo increased the dry matter yield of
shoot. Application of Mo increased the concentration of Mo and P in shoot. Applied P caused an increase in the concentration
of Mo, Zn and P in shoot. Combined application of P and Mo resulted in an increase in concentration and uptake of Mo in shoot. 相似文献