Cystathionine beta-synthase (CBS) condenses homocysteine, a toxic metabolite, with serine in a pyridoxal phosphate-dependent reaction. It also contains a heme cofactor to which carbon monoxide (CO) or nitric oxide can bind, resulting in enzyme inhibition. To understand the mechanism of this regulation, we have investigated the equilibria and kinetics of CO binding to the highly active catalytic core of CBS, which is dimeric. CBS exhibits strong anticooperativity in CO binding with successive association constants of 0.24 and 0.02 microm(-1). Stopped flow measurements reveal slow CO association (0.0166 s(-1)) limited by dissociation of the endogenous ligand, Cys-52. Rebinding of CO and of Cys-52 following CO photodissociation were independently monitored via time-resolved resonance Raman spectroscopy. The Cys-52 rebinding rate, 4000 s(-1), is essentially unchanged between pH 7.6 and 10.5, indicating that the pK(a) of Cys-52 is shifted below pH 7.6. This effect is attributed to the nearby Arg-266 residue, which is proposed to form a salt bridge with the dissociated Cys-52, thereby inhibiting its protonation and slowing rebinding to the Fe. This salt bridge suggests a pathway for enzyme inactivation upon CO binding, because Arg-266 is located on a helix that connects the heme and pyridoxal phosphate cofactor domains.
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http://dx.doi.org/10.1074/jbc.M600246200 | DOI Listing |
Environ Pollut
January 2025
Plant Physiology and Biochemistry Laboratory, Department of Botany, University of Delhi, Delhi 110007, India. Electronic address:
Urban air pollution has been a global challenge world-wide. While urban vegetation or forest modelling can be useful in reducing the toxicities of the atmospheric gases by their absorption, the surge in gaseous pollutants negatively affects plant growth, thereby altering photosynthetic efficiency and harvest index. The present review analyses our current understanding of the toxic and beneficial effects of atmospheric nitrogen oxides (NO), hydrogen sulphide (HS) and carbon monoxide (CO) on plant growth and metabolism.
View Article and Find Full Text PDFJ Hazard Mater
January 2025
State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026, PR China; Suzhou Key Laboratory for Urban Public Safety, Suzhou Institute for Advanced Research, University of Science and Technology of China, Suzhou, Jiangsu 215123, PR China. Electronic address:
The development of carbon monoxide oxidation catalysts for complex gas environments faces significant challenges in fire scenarios. Only a few representative gases are used as interfering components in simulated real smoke under laboratory conditions, which cannot accurately reflect the performance of catalysts in a real fire. Herein, Au/CeO catalysts with high activity were prepared by adjusting the morphology (rod, cube, polyhedron and irregular particles) and exposed crystal surface ratio of CeO.
View Article and Find Full Text PDFTransl Oncol
January 2025
Henan International Joint Laboratory for Nuclear Protein Regulation, School of Basic Medical Sciences, School of Stomatology, Henan University, Kaifeng, Henan 475004, China; Department of Stomatology, Huaihe Hospital of Henan University, School of Stomatology, Henan University, Kaifeng, Henan 475004, China. Electronic address:
The occurrence and development of tumor is mediated by a wide range of complex mechanisms. Subsequent to nitric oxide and carbon monoxide, hydrogen sulfide (HS) holds the distinction of being the third identified gasotransmitter. Alternation of HS level has been widely demonstrated to induce an array of disturbances in important cancer cell signaling pathways.
View Article and Find Full Text PDFERJ Open Res
January 2025
Department of Infectious Diseases, Respiratory Medicine and Critical Care, Charité - Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany.
Background: Data regarding the effectiveness and safety of endoscopic lung volume reduction with valves (ELVR) in emphysema patients with a very low 6-min walk test (6MWT) are limited. Patients with severe emphysema and very low exercise capacity, as indicated by a 6MWT ≤140 m, are often excluded from clinical studies on ELVR, assuming limited therapeutic benefits and increased complication risk.
Study Designs And Methods: This study utilised data from the Lungenemphysemregister e.
ERJ Open Res
January 2025
State Key Laboratory of Respiratory Disease & National Clinical Research Center for Respiratory Disease & Guangzhou Institute of Respiratory Health & National Center for Respiratory Medicine & Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, Guangdong, China.
Background: Small airway dysfunction (SAD) and impaired diffusion capacity of the lungs for carbon monoxide ( ) are positively associated with a worse prognosis. Individuals with both dysfunctions have been identified in clinical practice and it is unknown whether they have worse health status or need management. We conducted this study to explore the association between SAD and impaired , and the difference between the groups with two dysfunctions, with either one dysfunction and with no dysfunction.
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