Entropy Drives an Attached Water Molecule from the C- to N-Terminus on Protonated Proline

Prell, James S.; Correra, Thiago C.; Chang, Terrence M.; Biles, Jeffrey A.; Williams, Evan R.

doi:10.1021/ja106167d

Cited by 30 publications

(41 citation statements)

References 11 publications

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“…The weighted mean of the mean residue ellipticities for thermal unfolding of two proteins was calculated using the formula ((A*θ 1 ) + (B*θ 2 ))/ (A+B), where A and B are the number of amino acid residues in the individual proteins and θ 1 and θ 2 are the mean residue ellipticities at the melting temperature (T m ) for the respective proteins. The thermodynamic parameters of protein unfolding were calculated using the Van’t Hoff equation [15]. …”

Section: Methodsmentioning

confidence: 99%

Role of Neurotoxin Associated Proteins in the Low pH Induced Structural Changes in the Botulinum Neurotoxin Complex

Chellappan

Kumar²,

Cai

et al. 2014

Protein J

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BoNT (Botulinum Neurotoxin) produced by the bacterium Clostridium botulinum as a complex with NAPs causes botulism. It has been known that the NAPs protect the toxin from both extremes of pHs and proteases of the GI tract. In an attempt to emulate the physiological conditions encountered by the toxin, we examined BoNT/A, BoNT/A complex, and NAPs under different pH conditions and monitored their structural characteristics by far-UV CD and thermal denaturation analysis. BoNT/A complex showed the maximum CD signal with a molar ellipticity of −1.8 × 105 deg.cm2/dmol at 222 nm at both acidic and neutral pHs. Thermal denaturation analysis revealed NAPs to be the most stable amongst the three protein samples examined. Interestingly and quite uniquely, at pH 2.5, there was an increase in CD signal for BoNT complex as a function of temperature, which correlated with the NAPs profile, indicating a shielding effect of NAPs on BoNT complex at low pH. Calculation of the weighted mean of the ellipticities at the Tm for thermal unfolding of toxin and NAPs at neutral and acidic pHs showed variation with that of BoNT complex, suggesting structural reorganization in BoNT complex upon the association of NAPs and BoNT. In conclusion, this study reveals the structural behavior of BoNT complex and NAPs with pH changes substantially, which could be quite relevant for BoNT survival under extreme pH conditions in vivo.

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Section: Methodsmentioning

confidence: 99%

Role of Neurotoxin Associated Proteins in the Low pH Induced Structural Changes in the Botulinum Neurotoxin Complex

Chellappan

Kumar²,

Cai

et al. 2014

Protein J

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“…The largest systematic change is the ratio of relative abundances for these two peaks. Using the integrated areas of the Gaussian lineshapes, the hydrogen bonding network composition for n e = 45 is ∼40% amorphous at 135 K and becomes less ordered as the copper jacket temperature is elevated, which results in an increase of the amorphous contribution to ∼46% at 215 K. Because the intensity of absorptive bands can depend nonlinearly on single photon absorption cross sections using IRPD, 63 these integrated bands may provide a more qualitative than quantitative measure of structural change with increasing temperature. However, the increase in the ratio for amorphous to highly-ordered bands indicates that the nanodrop structures have less-optimal O–H–O hydrogen-bonding angles and a decrease in water molecule coordination.…”

Section: Resultsmentioning

confidence: 99%

Long distance ion–water interactions in aqueous sulfate nanodrops persist to ambient temperatures in the upper atmosphere

2018

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“…The experimental band that has a maximum near 3475 cm À1 corresponds to the O-H stretch of the second shell water molecule in isomer 5c that weakly H-bonds with nitrate and is predicted to occur at 3504 cm À1 . 70,71 For larger hydrates of SrNO 3 + and PbNO 3 + , a comparison between experiment and theory is more challenging owing to the increasing number of possible isomers and increasing computational difficulty with increasing cluster size. In general, the agreement between experimental and calculated frequencies and intensities is poorer in the bonded O-H region.…”

Section: Structures Of [Mno 3 ] + (H 2 O)mentioning

confidence: 99%

Effects of electronic structure on the hydration of PbNO₃⁺ and SrNO₃⁺ ion pairs

Cooper

Heiles

Williams

2015

Phys. Chem. Chem. Phys.

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Hydration of PbNO3(+) and SrNO3(+) with up to 30 water molecules was investigated with infrared photodissociation (IRPD) spectroscopy and with theory. These ions are the same size, yet the IRPD spectra of these ion pairs for n = 2-8 are significantly different. Bands in the bonded O-H region (∼3000-3550 cm(-1)) indicate that the onset of a second hydration shell begins at n = 5 for PbNO3(+) and n = 6 for SrNO3(+). Spectra for [PbNO3](+)(H2O)2-5 and [SrNO3](+)(H2O)3-6 indicate that the structures of clusters with Pb(ii) are hemidirected with a void in the coordinate sphere. A natural bond orbital analysis of [PbNO3](+)(H2O)5 indicates that the anisotropic solvation of the ion is due to a region of asymmetric electron density on Pb(ii) that can be explained by charge transfer from the nitrate and water ligands into unoccupied p-orbitals on Pb(ii). There are differences in the IRPD spectra of PbNO3(+) and SrNO3(+) with up to 25 water molecules attached. IR intensity in the bonded O-H region is blue-shifted by ∼50 cm(-1) in nanodrops containing SrNO3(+) compared to those containing PbNO3(+), indicative of a greater perturbation of the water H-bond network by strontium. The free O-H stretches of surface water molecules in nanodrops containing 10, 15, 20, and 25 water molecules are red-shifted by ∼3-8 cm(-1) for PbNO3(+) compared to those for SrNO3(+), consistent with more charge transfer between water molecules and Pb(ii). These results demonstrate that the different electronic structure of these ions significantly influences how they are solvated.

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Entropy Drives an Attached Water Molecule from the C- to N-Terminus on Protonated Proline

Cited by 30 publications

References 11 publications

Role of Neurotoxin Associated Proteins in the Low pH Induced Structural Changes in the Botulinum Neurotoxin Complex

Role of Neurotoxin Associated Proteins in the Low pH Induced Structural Changes in the Botulinum Neurotoxin Complex

Long distance ion–water interactions in aqueous sulfate nanodrops persist to ambient temperatures in the upper atmosphere

Effects of electronic structure on the hydration of PbNO₃⁺ and SrNO₃⁺ ion pairs

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Entropy Drives an Attached Water Molecule from the C- to N-Terminus on Protonated Proline

Cited by 30 publications

References 11 publications

Role of Neurotoxin Associated Proteins in the Low pH Induced Structural Changes in the Botulinum Neurotoxin Complex

Role of Neurotoxin Associated Proteins in the Low pH Induced Structural Changes in the Botulinum Neurotoxin Complex

Long distance ion–water interactions in aqueous sulfate nanodrops persist to ambient temperatures in the upper atmosphere

Effects of electronic structure on the hydration of PbNO3+ and SrNO3+ ion pairs

Contact Info

Product

Resources

About

Effects of electronic structure on the hydration of PbNO₃⁺ and SrNO₃⁺ ion pairs