The activity of ribose-5-phosphate isomerases (RpiB) from Clostridium difficile for D-ribose isomerization was optimal at pH 7.5 and 40 degrees C, while that from Thermotoga maritima for L-talose isomerization was optimal at pH 8.0 and 70 degrees C. C. difficile RpiB exhibited activity only with aldose substrates possessing hydroxyl groups oriented in the right-handed configuration (Fischer projections) at the C2 and C3 positions, such as D-ribose, D-allose, L-talose, L-lyxose, D-gulose, and L-mannose. In contrast, T. maritima RpiB displayed activity only with aldose substrates possessing hydroxyl groups configured the same direction at the C2, C3, and C4 positions, such as the D- and L-forms of ribose, talose, and allose.
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http://dx.doi.org/10.1007/s10529-010-0224-x | DOI Listing |
Int J Mol Sci
November 2024
School of Biological Sciences, University of the Punjab, Lahore 54590, Pakistan.
Phosphopentomutases catalyze the isomerization of ribose 1-phosphate and ribose 5-phosphate. , a hyperthermophilic archaeon, harbors a novel enzyme (PPM) that exhibits high homology with phosphohexomutases but has no significant phosphohexomutase activity. Instead, PPM catalyzes the interconversion of ribose 1-phosphate and ribose 5-phosphate.
View Article and Find Full Text PDFInt J Biol Macromol
December 2024
School of Chemistry and Life Sciences, Suzhou University of Science and Technology, Suzhou 215009, China. Electronic address:
The cascade of sugar isomerases is one of the most practical methods for producing rare sugars, and enzyme immobilization endows it with high economic efficiency, operational convenience and reusability. However, the most employed cross-linker glutaraldehyde (GA) has the disadvantages of enzyme deactivation and limitation of substrate binding. Herein, three compounds, glyoxal, GA, and 2,5-furandicarboxaldehyde (DFF) were evaluated within a previously developed cascade comprising ribose-5-phosphate isomerase and D-tagatose-3-epimerase to prepare D-ribulose form D-xylose.
View Article and Find Full Text PDFCells
November 2024
Engelhardt Institute of Molecular Biology, Russian Academy of Science, 119991 Moscow, Russia.
In cells, the main enzymes involved in pentose interconversion are ribose-5-phosphate isomerases RpiA and RpiB and ribulose-5-phosphate epimerase Rpe. The inactivation of limits ribose-5-phosphate (R5P) synthesis via the oxidative branch of the pentose phosphate pathway (PPP) and unexpectedly results in antibiotic supersensitivity. This type of metabolism is accompanied by significant changes in the level of reducing equivalents of NADPH and glutathione, as well as a sharp drop in the ATP pool.
View Article and Find Full Text PDFCommun Biol
November 2024
MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, USA.
EMBO J
July 2024
Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research and Department of Molecular and Translational Sciences, Monash University, Clayton, VIC, 3168, Australia.
During infection viruses hijack host cell metabolism to promote their replication. Here, analysis of metabolite alterations in macrophages exposed to poly I:C recognises that the antiviral effector Protein Kinase RNA-activated (PKR) suppresses glucose breakdown within the pentose phosphate pathway (PPP). This pathway runs parallel to central glycolysis and is critical to producing NADPH and pentose precursors for nucleotides.
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