Sol–gel encapsulation of metalloproteins for the development of optical biosensors for nitrogen monoxide and carbon monoxide

Blyth, David J.; Aylott, Jonathan W.; Richardson, David J.; Russell, David A.

doi:10.1039/an9952002725

Cited by 100 publications

(98 citation statements)

References 17 publications

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“…The binding of CO to ferrous heme can occur either at a vacant sixth co-ordination site or by displacement of an axial ligand from the polypeptide chain. Expected spectral shifts upon CO ligation to reduced c-type cytochromes are increases in the ␣-and ␤-band wavelength maxima accompanied by a decrease in the ␥-band wavelength maximum (21). The traces obtained for the reduced 20-and 85-kDa cytochromes in the presence of CO show a combination of features in the ␣,␤-region that represent both ferrous heme and CO-ligated ferrous heme.…”

Section: Membranous Cytochromes Present In Shewanella Species-mentioning

confidence: 94%

Purification and Magneto-optical Spectroscopic Characterization of Cytoplasmic Membrane and Outer Membrane Multiheme c-Type Cytochromes from Shewanella frigidimarina NCIMB400

Field

Dobbin

Cheesman

et al. 2000

Journal of Biological Chemistry

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107

108

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Two membranous c-type cytochromes from the Fe(III)-respiring bacterium Shewanella frigidimarina NCIMB400, CymA and OmcA, have been purified and characterized by UV-visible, magnetic circular dichroism, and electron paramagnetic resonance spectroscopies. The 20-kDa CymA is a member of the NapC/NirT family of multiheme cytochromes, which are invariably anchored to the cytoplasmic membrane of Gram-negative bacteria, and are postulated to mediate electron flow between quinols and periplasmic redox proteins. CymA was found to contain four low-spin c-hemes, each with bis-His axial ligation, and midpoint reduction potentials of ؉10, ؊108, ؊136, and ؊229 mV. The 85-kDa OmcA is located at the outer membrane of S. frigidimarina NCIMB400, and as such might function as a terminal reductase via interaction with insoluble Fe(III) substrates. This putative role is supported by the finding that the protein was released into solution upon incubation of harvested intact cells at 25°C, suggesting an attachment to the exterior face of the outer membrane. OmcA was revealed by magneto-optical spectrocopies to contain 10 low-spin bis-His ligated c-hemes, with the redox titer indicating two sets of near iso-potential components centered at ؊243 and ؊324 mV.

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Section: Membranous Cytochromes Present In Shewanella Species-mentioning

confidence: 94%

Purification and Magneto-optical Spectroscopic Characterization of Cytoplasmic Membrane and Outer Membrane Multiheme c-Type Cytochromes from Shewanella frigidimarina NCIMB400

Field

Dobbin

Cheesman

et al. 2000

Journal of Biological Chemistry

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107

108

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“…Silica gels have been shown to be chemically inert and to allow proteins to be incorporated retaining their specificity and reactivity (30 -38). In particular, glass-encapsulated myoglobin and hemoglobin maintain their chemical and spectroscopic properties (31)(32)(33)36) and have been used for the development of optical biosensors for the quantitative determination of oxygen, nitrogen monoxide, and carbon monoxide (31)(32)(33). Similar to hemoglobin crystals, wet silica gels contain about 50% water and 50% protein.…”

mentioning

confidence: 99%

T State Hemoglobin Binds Oxygen Noncooperatively with Allosteric Effects of Protons, Inositol Hexaphosphate, and Chloride

Bettati

Mozzarelli

1997

Journal of Biological Chemistry

129

122

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Hemoglobin is the paradigm of allosteric proteins. Over the years, cooperative oxygen binding has been explained by different models predicting that the T state of hemoglobin binds oxygen either noncooperatively or with some degree of cooperativity or with strong cooperativity. Therefore, a critical test that discriminates among models is to determine the oxygen binding by the T state of hemoglobin. Fixation of hemoglobin in the T state has been achieved either by crystallization from polyethylene glycol solutions or by encapsulation in wet porous silica gels. Hemoglobin crystals bind oxygen noncooperatively with reduced affinity compared with solution, with no Bohr effect and with no influence of other allosteric effectors. In this study, we have determined accurate oxygen-binding curves to the T state of hemoglobin in silica gels with the same microspectrophotometric apparatus and multiwavelengths analysis used in crystal experiments. The T state of hemoglobin in silica gels binds oxygen noncooperatively with an affinity and a Bohr effect similar to those observed in solution for the binding of the first oxygen molecule. Other allosteric effectors such as inositol hexaphosphate, bezafibrate, and chloride significantly affect oxygen affinity. Therefore, T state hemoglobins that are characterized by strikingly different functional properties share the absence of cooperativity in the binding of oxygen. These findings are fully consistent with the Monod, Wyman, and Changeux model and with most features of Perutz's stereochemical model, but they are not consistent with models of both Koshland and Ackers.Hemoglobin binds oxygen cooperatively with an affinity that is regulated by protons, organic phosphates, chloride, and carbon dioxide (1, 2). These properties are associated to the peculiar structure of the T quaternary state since the R quaternary state exhibits functional properties similar to those of isolated ␣-␤ dimers and isolated chains. For this reason, a great effort has been devoted to functionally and structurally characterize the T state and pathway from deoxyhemoglobin to oxyhemoglobin (1-4, 11, 12). Along this pathway, oxygen binding leads to tertiary conformational changes and to the quaternary transition whose relevance to the functional properties of hemoglobin is model-dependent. In fact, according to the Monod, Wyman, and Changeux model (5-7), hemoglobin exists in two quaternary states, a low affinity T state and a high affinity R state. Ligand binding to either the T or the R state is predicted to be noncooperative. The progressive shift of the T-R equilibrium in favor of the R state as a function of ligand saturation accounts for the positive cooperativity. The Monod, Wyman, and Changeux model has been extended to include the effect of allosteric ligands on the T state affinity (3, 8) and to fit nanosecond-millisecond kinetics of ligand binding as well as equilibrium data simultaneously (9). Furthermore, the extensive investigation of structural, spectroscopic, and functional properties of hemog...

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“…It may also be possible to use the cyt. c-SiO 2 aerogels to detect the presence of other ligands such as carbon monoxide 27 . Different published procedures include an added step of combining gold or silver nanoparticles with cyt.…”

Section: Discussionmentioning

confidence: 99%

“…c being encapsulated in sol-gels that have been kept wet or that have been dried ambiently [24][25][26][27][28][29][30] . Reports of encapsulating biomolecules in sol-gels that are then dried supercritically to form aerogels are rarer due to the necessary processing that can be detrimental to the structure of many proteins.…”

Section: Introductionmentioning

confidence: 99%

Encapsulating Cytochrome <em>c</em> in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity

Harper-Leatherman

Pacer

Kosciuszek

2016

JoVE

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Applications such as sensors, batteries, and fuel cells have been improved through the use of highly porous aerogels when functional compounds are encapsulated within the aerogels. However, few reports on encapsulating proteins within sol-gels that are processed to form aerogels exist. A procedure for encapsulating cytochrome c (cyt. c) in silica (SiO 2 ) sol-gels that are supercritically processed to form bioaerogels with gas-phase activity for nitric oxide (NO) is presented. Cyt. c is added to a mixed silica sol under controlled protein concentration and buffer strength conditions. The sol mixture is then gelled and the liquid filling the gel pores is replaced through a series of solvent exchanges with liquid carbon dioxide. The carbon dioxide is brought to its critical point and vented off to form dry aerogels with cyt. c encapsulated inside. These bioaerogels are characterized with UV-visible spectroscopy and circular dichroism spectroscopy and can be used to detect the presence of gas-phase nitric oxide. The success of this procedure depends on regulating the cyt. c concentration and the buffer concentration and does not require other components such as metal nanoparticles. It may be possible to encapsulate other proteins using a similar approach making this procedure important for potential future bioanalytical device development.

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Sol–gel encapsulation of metalloproteins for the development of optical biosensors for nitrogen monoxide and carbon monoxide

Cited by 100 publications

References 17 publications

Purification and Magneto-optical Spectroscopic Characterization of Cytoplasmic Membrane and Outer Membrane Multiheme c-Type Cytochromes from Shewanella frigidimarina NCIMB400

Purification and Magneto-optical Spectroscopic Characterization of Cytoplasmic Membrane and Outer Membrane Multiheme c-Type Cytochromes from Shewanella frigidimarina NCIMB400

T State Hemoglobin Binds Oxygen Noncooperatively with Allosteric Effects of Protons, Inositol Hexaphosphate, and Chloride

Encapsulating Cytochrome <em>c</em> in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity

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