Query: carbon monoxide

title: THE CARBON MONOXIDE BINDING PIGMENT OF LIVER MICROSOMES. I. EVIDENCE FOR ITS HEMOPROTEIN NATURE.
abstract: The presence in mammalian liver microsomes of a carbon monoxide binding pigment has been reported by Klingenberg (1) and by Garfinkel (2) The CO compound of the reduced pigment has an intense absorption band at 450 rnl.c and thus can be readily detected in dithionite treated microsomes by difference spectrophotometry. The CO difference spectrum of reduced microsomes is, however, unusual in that it shows no peaks other than that at 450 rnp and, therefore, provides no clue to the nature of the pigment. The elucidation of its nature has further been hampered by the reported lability of the microsomal pigment to detergents, low pH, and enzymatic digestion (1,2) In addition, the CO compound has been reported as not photodissociable (1) In preliminary communications (3, 4) we have reported evidence for the hemoprotein nature of the microsomal CObinding pigment, provisionally called "P 450," and shown that it can be converted into a solubilised form, which we term "P420," by treatment of microsomes anaerobically with snake venom or deosycholate. The solubiliaation is accompanied by an unusual change in the spectral properties of the pigment. Further, the solubilized pigment has been partly purified, free from cytochrome 55, and shown to possess absorption spectra characteristic of hemoproteins (5) The present paper gives a detailed account of the investigations on rabbit liver microsomes and crude microsomal digests, which have led us to postulate the hemoprotein nature of the pigment. Purification and properties of the solubilized hemoprotein will be reported in the accompanying paper (6)

title: 2017 ERS/ATS standards for single breath carbon monoxide uptake in the lung
abstract: This document provides an update to the European Respiratory Society (ERS)/American Thoracic Society (ATS) technical standards for single breath carbon monoxide uptake in the lung that was last updated in 2005. Although both DLCO (diffusing capacity) and TLCO (transfer factor) are valid terms to describe the uptake of carbon monoxide in the lung, the term DLCO is used in this document. A joint taskforce appointed by the ERS and ATS reviewed the recent literature on the measurement of DLCO and surveyed the current technical capabilities of instrumentation being manufactured around the world. The recommendations in this document represent the consensus of the taskforce members in regard to the evidence available for various aspects of DLCO measurement. Furthermore, it reflects the expert opinion of the taskforce members on areas in which peer reviewed evidence was either not available or was incomplete. The major changes in these technical standards relate to DLCO measurement with systems using rapidly responding gas analysers for carbon monoxide and the tracer gas, which are now the most common type of DLCO instrumentation being manufactured. Technical improvements and the increased capability afforded by these new systems permit enhanced measurement of DLCO and the opportunity to include other optional measures of lung function. Updated technical standards for measuring DLCO (TLCO) including the use of rapid gas analyser systems http:/ow.ly/QUhv304PMsy

title: Executive Summary: 2017 ERS/ATS standards for single breath carbon monoxide uptake in the lung
abstract: This document summarises an update to the European Respiratory Society (ERS)/American Thoracic Society (ATS) technical standards for single breath carbon monoxide uptake in the lung that was last updated in 2005. The full standards are also available online as https:/doi.org/10.1183/13993003.00016 2016. The major changes in these technical standards relate to DLCO measurement with systems using rapidly responding gas analysers for carbon monoxide and the tracer gas, which are now the most common type of DLCO instrumentation being manufactured. Technical improvements and the increased capability afforded by these new systems permit enhanced measurement of DLCO and the opportunity to include other optional measures of lung function. Summary of updated technical standards for measuring DLCO (TLCO) including the use of rapid gas analyser systems http:/ow.ly/TQVG305g3Zq

title: Biological signaling by carbon monoxide and carbon monoxide releasing molecules.
abstract: Carbon monoxide (CO) is continuously produced in mammalian cells during the degradation of heme. It is a stable gaseous molecule that reacts selectively with transition metals in a specific redox state, and these characteristics restrict the interaction of CO with defined biological targets that transduce its signaling activity. Because of the high affinity of CO for ferrous heme, these targets can be grouped into heme containing proteins, representing a large variety of sensors and enzymes with a series of diverse function in the cell and the organism. Despite this notion, progress in identifying which of these targets are selective for CO has been slow and even the significance of elevated carbonmonoxy hemoglobin, a classical marker used to diagnose CO poisoning, is not well understood. This is also due to the lack of technologies capable of assessing in a comprehensive fashion the distribution and local levels of CO between the blood circulation, the tissue, and the mitochondria, one of the cellular compartments where CO exerts its signaling or detrimental effects. Nevertheless, the use of CO gas and CO releasing molecules as pharmacological approaches in models of disease has provided new important information about the signaling properties of CO. In this review we will analyze the most salient effects of CO in biology and discuss how the binding of CO with key ferrous hemoproteins serves as a posttranslational modification that regulates important processes as diverse as aerobic metabolism, oxidative stress, and mitochondrial bioenergetics.

title: Electrocatalytic reduction of carbon dioxide to carbon monoxide and methane at an immobilized cobalt protoporphyrin
abstract: The electrochemical conversion of carbon dioxide and water into useful products is a major challenge in facilitating a closed carbon cycle. Here we report a cobalt protoporphyrin immobilized on a pyrolytic graphite electrode that reduces carbon dioxide in an aqueous acidic solution at relatively low overpotential (0.5 V) with an efficiency and selectivity comparable to the best porphyrin based electrocatalyst in the literature. While carbon monoxide is the main reduction product, we also observe methane as by product. The results of our detailed pH dependent studies are explained consistently by a mechanism in which carbon dioxide is activated by the cobalt protoporphyrin through the stabilization of a radical intermediate, which acts as Bronsted base. The basic character of this intermediate explains how the carbon dioxide reduction circumvents a concerted proton electron transfer mechanism, in contrast to hydrogen evolution. Our results and their mechanistic interpretations suggest strategies for designing improved catalysts.

title: Electroreduction of carbon monoxide to liquid fuel on oxide derived nanocrystalline copper
abstract: The electrochemical conversion of CO2 and H2O into liquid fuel is ideal for high density renewable energy storage and could provide an incentive for CO2 capture. However, efficient electrocatalysts for reducing CO2 and its derivatives into a desirable fuel are not available at present. Although many catalysts can reduce CO2 to carbon monoxide (CO) liquid fuel synthesis requires that CO is reduced further, using H2O as a H+ source. Copper (Cu) is the only known material with an appreciable CO electroreduction activity, but in bulk form its efficiency and selectivity for liquid fuel are far too low for practical use. In particular, H2O reduction to H2 outcompetes CO reduction on Cu electrodes unless extreme overpotentials are applied, at which point gaseous hydrocarbons are the major CO reduction products. Here we show that nanocrystalline Cu prepared from Cu2O 'oxide derived Cu' produces multi carbon oxygenates (ethanol, acetate and n propanol) with up to 57% Faraday efficiency at modest potentials 0.25 volts to 0.5 volts versus the reversible hydrogen electrode) in CO saturated alkaline H2O. By comparison, when prepared by traditional vapour condensation, Cu nanoparticles with an average crystallite size similar to that of oxide derived copper produce nearly exclusive H2 (96% Faraday efficiency) under identical conditions. Our results demonstrate the ability to change the intrinsic catalytic properties of Cu for this notoriously difficult reaction by growing interconnected nanocrystallites from the constrained environment of an oxide lattice. The selectivity for oxygenates, with ethanol as the major product, demonstrates the feasibility of a two step conversion of CO2 to liquid fuel that could be powered by renewable electricity.

title: Carbon monoxide physiology, detection and controlled release.
abstract: Carbon monoxide (CO) is increasingly recognized as a cell signalling molecule akin to nitric oxide (NO) CO has attracted particular attention as a potential therapeutic agent because of its reported anti hypertensive, anti inflammatory and cell protective effects. We discuss recent progress in identifying new effector systems and elucidating the mechanisms of action of CO on, e.g. ion channels, as well as the design of novel methods to monitor CO in cellular environments. We also report on recent developments in the area of CO releasing molecules (CORMs) and materials for controlled CO application. Novel triggers for CO release, metal carbonyls and degradation mechanisms of CORMs are highlighted. In addition, potential formulations of CORMs for targeted CO release are discussed.

title: Detection of Carbon Monoxide and Water Absorption Lines in an Exoplanet Atmosphere
abstract: High Resolution Spectrum of an Exoplanet Unlike most of the extrasolar planets we know about, the four planets around the star HR 8799 were detected directly. Konopacky et al. (p. 1398, published online 14 March; see the Perspective by Marley) obtained a high resolution spectrum of one of the planets that reveals both water and carbon monoxide but not methane in the planet's atmosphere. The atmospheric carbon to oxygen ratio, which traces the process of planet formation, is greater than that of the host star, providing clues to how the planets formed. A high resolution spectrum of an exoplanet reveals molecular lines that provide clues about the planet's formation.  Determining the atmospheric structure and chemical composition of an exoplanet remains a formidable goal. Fortunately, advancements in the study of exoplanets and their atmospheres have come in the form of direct imaging spatially resolving the planet from its parent star which enables high resolution spectroscopy of self luminous planets in jovian like orbits. Here, we present a spectrum with numerous, well resolved molecular lines from both water and carbon monoxide from a massive planet orbiting less than 40 astronomical units from the star HR 8799. These data reveal the planet's chemical composition, atmospheric structure, and surface gravity, confirming that it is indeed a young planet. The spectral lines suggest an atmospheric carbon to oxygen ratio that is greater than that of the host star, providing hints about the planet's formation.

title: Catalytic Oxidation of Carbon Monoxide over Transition Metal Oxides
abstract: Oxidation into CO2 is a major solution to CO abatement in air depollution treatments. The development of catalytic converters led to an extraordinary high number of publications on metal catalysts during the last fifty years. Due to the increasing price of noble metals and to remarkable progresses in oxide syntheses, catalytic oxidation of carbon monoxide over oxide catalysts has recently gained in interest, even if some oxides are known to present remarkable activity since the beginning of the 20th century. In this Review, the kinetics and mechanism of CO oxidation on single and mixed oxides are examined, alongside the catalyst structures.

title: Pits confined in ultrathin cerium(IV) oxide for studying catalytic centers in carbon monoxide oxidation.
abstract: Finding ideal material models for studying the role of catalytic active sites remains a great challenge. Here we propose pits confined in an atomically thin sheet as a platform to evaluate carbon monoxide catalytic oxidation at various sites. The artificial three atomic layer thin cerium(IV) oxide sheet with approximately 20% pits occupancy possesses abundant pit surrounding cerium sites having average coordination numbers of 4.6 as revealed by X ray absorption spectroscopy. Density functional calculations disclose that the four and five fold coordinated pit surrounding cerium sites assume their respective role in carbon monoxide adsorption and oxygen activation, which lowers the activation barrier and avoids catalytic poisoning. Moreover, the presence of coordination unsaturated cerium sites increases the carrier density and facilitates carbon monoxide diffusion along the two dimensional conducting channels of surface pits. The atomically thin sheet with surface confined pits exhibits lower apparent activation energy than the bulk material (61.7 versus 122.9 kJ mol( 1) leading to reduced conversion temperature and enhanced carbon monoxide catalytic ability.