Spectroscopic markers of the T↔R quaternary transition in human hemoglobin

Schirò, Giorgio; Cammarata, Marco; Levantino, Matteo; Cupane, Antonio

doi:10.1016/j.bpc.2004.11.005

Cited by 9 publications

(9 citation statements)

References 43 publications

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“…In fact, proteins trapped within silica gel are characterized by some interesting properties: a comparison with standard solution conditions reveals that in silica gel proteins retain their functional properties and structure-sensitive optical spectral features are nearly identical to those measured in solution [1][2][3][4][5], whereas a dramatic slowing down of protein dynamics is observed, the extent of slowing down depending on encapsulation protocol and solvent composition [6,7,27]. The physical origin of such an effect on protein dynamics without any significant structural/conformational perturbation is far to be fully understood.…”

Section: Introductionmentioning

confidence: 93%

“…Encapsulation of glycerol/water systems in silica gels was performed using the following protocol, closely analogous to that we adopted to encapsulate proteins [3,10]: a solution containing 60% v/v TMOS, 38% v/v water and 2% v/v HCl 0.04 M was sonicated for 20 min in an ice bath; immediately after sonication it was mixed in a 3:2 proportion (in volume) and at 7°C with a glycerol/water solution at 22 mol% of glycerol and 0.2 M K-phosphate buffer pH 7. In these conditions formation of a 1 mm thick gel occurred in about 1 min.…”

Section: Samplesmentioning

confidence: 99%

See 1 more Smart Citation

Dynamic properties of solvent confined in silica gels studied by broadband dielectric spectroscopy

Schirò

Cupane

Pagnotta

et al. 2007

Journal of Non-Crystalline Solids

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Section: Introductionmentioning

confidence: 93%

Section: Samplesmentioning

confidence: 99%

Dynamic properties of solvent confined in silica gels studied by broadband dielectric spectroscopy

Schirò

Cupane

Pagnotta

et al. 2007

Journal of Non-Crystalline Solids

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“…[5][6][7][8][9][10][11][12][13] In addition, tertiary and quaternary conformational changes in heme proteins, such as myoglobin (Mb) and hemoglobin (Hb), can be inhibited or dramatically slowed, which allows these proteins to be "trapped" and studied in non-equilibrium structural conformations. [14][15][16][17][18][19][20][21][22] The origin of the stability imparted by the silica sol-gel matrix is complex. Since the mean pore diameters in aged wet sol-gels (typically <10 nm) are comparable to the diameters of Mb and Hb, the pore walls could physically restrict protein motions.…”

Section: Introductionmentioning

confidence: 99%

“…Silica sol−gel glasses consist of nanoporous networks with interpore connections that permit the exchange of solvent and small molecules while inhibiting the transport of larger species . It has been broadly shown that the overall stability of proteins and enzymes embedded in these glasses is enhanced with regard to temperature, pH, and chemical denaturation. − In addition, tertiary and quaternary conformational changes in heme proteins, such as myoglobin (Mb) and hemoglobin (Hb), can be inhibited or dramatically slowed, which allows these proteins to be “trapped” and studied in nonequilibrium structural conformations. − …”

Section: Introductionmentioning

confidence: 99%

Dynamics of Proteins Encapsulated in Silica Sol−Gel Glasses Studied with IR Vibrational Echo Spectroscopy

2006

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Spectrally-resolved infrared stimulated vibrational echo spectroscopy is used to measure the fast dynamics of heme-bound CO in carbonmonoxy-myoglobin (MbCO) and hemoglobin (HbCO) embedded in silica sol-gel glasses. On the time scale of ~100 fs to several ps, the vibrational dephasing of the heme-bound CO is measurably slower for both MbCO and HbCO relative to aqueous protein solutions. The fast structural dynamics of MbCO, as sensed by the heme-bound CO, are influenced more by the sol-gel environment than those of HbCO. Longer time scale structural dynamics (tens of ps), as measured by the extent of spectral diffusion, are the same for both proteins encapsulated in sol-gel glasses compared to aqueous solutions. A comparison of the sol-gel experimental results to viscosity dependent vibrational echo data taken on various mixtures of water and fructose shows that the sol-gel encapsulated MbCO exhibits dynamics that are the equivalent to the protein in a solution that is nearly 20 times more viscous than bulk water. In contrast, the HbCO dephasing in the sol-gel reflects only a 2-fold increase in viscosity. Attempts to alter the encapsulating pore size by varying the molar ratio of silane precursor to water (R-value) used to prepare the sol-gel glasses were found to have no effect on the fast or steady-state spectroscopic results. The vibrational echo data are discussed in the context of solvent confinement and protein-pore wall interactions to provide insights into the influence of a confined environment on the fast structural dynamics experienced by a biomolecule.

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“…The possibility provided by silica gel encapsulation to reduce the rate of conformational changes by orders of magnitude, increasing the kinetic separation of tertiary and quaternary relaxations [57,58,[80][81][82][83][84][85][86][87][88][89][90][91][92], has been extensively exploited by several groups to make accessible to spectroscopic investigation species that are normally poorly populated, or metastable on the time scale of solution experiments. Not surprisingly, many of these studies concern hemoglobin (Hb), myoglobin and other heme binding proteins, since the availability of a sensitive, intrinsic chromophoric signal allowed to achieve an unprecedented level of detail in the comprehension of structure-dynamic-function relationships.…”

Section: Heme Proteinsmentioning

confidence: 99%

Immobilization of Proteins in Silica Gel: Biochemical and Biophysical Properties

Ronda

Bruno

Campanini

et al. 2015

COC

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Abstract:The development of silica-based sol-gel techniques compatible with the retention of protein structure and function started more than 20 years ago, mainly for the design of biotechnological devices or biomedical applications. Silica gels are optically transparent, exhibit good mechanical stability, are manufactured with different geometries, and are easily separated from the reaction media. Biomolecules encapsulated in silica gel normally retain their structural and functional properties, are stabilized with respect to chemical and physical insults, and can sometimes exhibit enhanced activity in comparison to the soluble form. This review briefly describes the chemistry of protein encapsulation within the pores of a silica gel three-dimensional network, the mechanism of interaction between the protein and the gel matrix, and its effects on protein structure, function, stability and dynamics. The main applications in the field of biosensor design are described. Special emphasis is devoted to silica gel encapsulation as a tool to selectively stabilize subsets of protein conformations for biochemical and biophysical studies, an application where silica-based encapsulation demonstrated superior performance with respect to other immobilization techniques.

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Spectroscopic markers of the T↔R quaternary transition in human hemoglobin

Cited by 9 publications

References 43 publications

Dynamic properties of solvent confined in silica gels studied by broadband dielectric spectroscopy

Dynamic properties of solvent confined in silica gels studied by broadband dielectric spectroscopy

Dynamics of Proteins Encapsulated in Silica Sol−Gel Glasses Studied with IR Vibrational Echo Spectroscopy

Immobilization of Proteins in Silica Gel: Biochemical and Biophysical Properties

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