Protein hydration from water oxygen-17 magnetic relaxation

Halle, Bertil; Andersson, Thomas; Forsén, Sture; Lindman, Bjoern

doi:10.1021/ja00393a004

Cited by 202 publications

(140 citation statements)

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“…Rather, we focus on the more readily interpreted 17 O relaxation data reported earlier (Halle et al, 1981;. While essentially the same conclusions as here were reached about the fast rotation of surface water molecules, it was also shown that the low-frequency relaxation contribution (b term) could be consistently accounted for in terms of the same (weakly ordered) surface water molecules whose fast (but orientationally restricted) rotation is responsible for the high-frequency contribution (a term).…”

Section: Concluding Discussionsupporting

confidence: 71%

“…In connection with previous 17 O relaxation studies, two weighty arguments were advanced in favor of a relaxation dispersion induced by a weakly ordered hydration layer (Halle et al, 1981;. First, the normalized relaxation dispersion step did not vary much among the half-dozen proteins examined, contrary to what would be expected if the dispersion was due to a small number of highly ordered water molecules in specific binding sites.…”

Section: Introductionmentioning

confidence: 92%

“…An alternative interpretation of the parameter b is possible (Halle et al, 1981;. If all protein-associated water molecules, including any rapidly exchanging internal water molecules are weakly ordered (A 1), then b is essentially due to the more numerous surface water molecules.…”

Section: Oxygen-17 Spin Relaxation Of Water In Protein Solutionsmentioning

confidence: 99%

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Protein Hydration Dynamics in Aqueous Solution: A Comparison of Bovine Pancreatic Trypsin Inhibitor and Ubiquitin by Oxygen-17 Spin Relaxation Dispersion

Денисов

Halle

1995

Journal of Molecular Biology

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162

177

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Water oxygen-17 spin relaxation was used to study hydration and dynamics Condensed Matter Magnetic Resonance Group, Chemical of the globular proteins bovine pancreatic trypsin inhibitor (BPTI) and ubiquitin in aqueous solution. The frequency dispersion of the longitudinal Center, Lund University P. O. Box 124, S-22100 Lund and transverse relaxation rates was measured over the Larmor frequency Sweden range 2.6 to 49 MHz in the pD range 2 to 11 at 27°C. While the protein-induced relaxation enhancement was similar for the two proteins at high frequencies, it was an order of magnitude smaller for ubiquitin than for BPTI at low frequencies. This difference was ascribed to the abscence, in ubiquitin, of highly ordered internal water molecules, which are known to be present in BPTI and in most other globular proteins. These observations demonstrate that the water relaxation dispersion in protein solutions is essentially due to a few structural water molecules buried within the protein matrix, but exchanging rapidly with the external water. The relaxation data indicate that the internal water molecules of BPTI exchange with bulk water on the time-scale 10 −8 to 10 −6 second thus lowering the recently reported upper bound on the residence time of these internal water molecules by four orders of magnitude, and implying that local unfolding occurs on the submicrosecond time-scale. The water molecules residing at the surface of the two proteins were found to be highly mobile, with an average rotational correlation time of approximately 20 picoseconds. For both proteins, the oxygen-17 relaxation depended only very weakly on pD, showing that ionic residues do not perturb hydration water dynamics more than other surface residues. We believe that the present results resolve the long-standing controversy regarding the mechanism behind the spin relaxation dispersion of water nuclei in protein solutions, thus establishing oxygen-17 relaxation as a powerful tool for studies of structurally and functionally important water molecules in proteins and other biomolecules.

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Section: Concluding Discussionsupporting

confidence: 71%

Section: Introductionmentioning

confidence: 92%

See 1 more Smart Citation

Protein Hydration Dynamics in Aqueous Solution: A Comparison of Bovine Pancreatic Trypsin Inhibitor and Ubiquitin by Oxygen-17 Spin Relaxation Dispersion

Денисов

Halle

1995

Journal of Molecular Biology

Self Cite

162

177

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“…NMR studies of protein hydration in aqueous solution give a range of residence times, 10 Ϫ2 -10 Ϫ8 , for interior water and subnanosecond for surface water, as shown by the groups of Wüthrich (12) and Forsén (33) and others. Because of the femtosecond resolution achieved here, we decided to reexamine the same protein, but when denatured.…”

Section: Resultsmentioning

confidence: 78%

Biological water at the protein surface: Dynamical solvation probed directly with femtosecond resolution

Pal

Peón

Zewail

2002

Proc. Natl. Acad. Sci. U.S.A.

530

578

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Biological water at the interface of proteins is critical to their equilibrium structures and enzyme function and to phenomena such as molecular recognition and protein-protein interactions. To actually probe the dynamics of water structure at the surface, we must examine the protein itself, without disrupting the native structure, and the ultrafast elementary processes of hydration. Here we report direct study, with femtosecond resolution, of the dynamics of hydration at the surface of the enzyme protein Subtilisin Carlsberg, whose single Trp residue (Trp-113) was used as an intrinsic biological fluorescent probe. For the protein, we observed two well separated dynamical solvation times, 0.8 ps and 38 ps, whereas in bulk water, we obtained 180 fs and 1.1 ps. We also studied a covalently bonded probe at a separation of Ϸ7 Å and observed the near disappearance of the 38-ps component, with solvation being practically complete in (time constant) 1.5 ps. The degree of rigidity of the probe (anisotropy decay) and of the water environment (protein vs. micelle) was also studied. These results show that hydration at the surface is a dynamical process with two general types of trajectories, those that result from weak interactions with the selected surface site, giving rise to bulk-type solvation (Ϸ1 ps), and those that have a stronger interaction, enough to define a rigid water structure, with a solvation time of 38 ps, much slower than that of the bulk. At a distance of Ϸ7 Å from the surface, essentially all trajectories are bulk-type. The theoretical framework for these observations is discussed.W ater is essential for the stability and function of biological macromolecules, proteins and DNA. Hydration plays a major role in the assembly of a protein's structure and dynamics. For example, water molecules around hydrophobic and hydrophilic sites are important to the understanding of the activity of enzyme proteins (see, e.g., refs. 1-3) and are part of the recognition process by other molecules or proteins. The water molecules that make up the hydration shell in the immediate vicinity of the surface are particularly relevant to the function and, in that sense, are termed biological water; this distinction has been discussed clearly by Nandi and Bagchi (4) in relation to dielectric relaxations. The nature of this shell ''layer'' has been the focus of numerous studies both theoretically and experimentally (see refs. 5-12), yet there is no generalized picture of the dynamics at the local molecular level.X-ray crystallography, neutron diffraction, and molecular dynamics studies have shown (5-10) that at protein surfaces, water molecules are site-selective and can be restricted in their motion, even existing in the form of clusters in some cases. For example, neutron diffraction experiments (9) followed by molecular dynamics simulations on carboxymyoglobin (10) revealed that among the 89 water molecules associated with the protein, 4 remain bound during the entire length of the molecular dynamics simulation (50 ps), whereas ...

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“…In fact, the percentage of apolar amino acid residues that are associated with protein hydrophobicity are about 50 and 37% for BSA and IgG, respectively, suggesting that BSA-covered beads are more hydrophobic. 46 Figure 6.10 reveals that the spherical geometry of Pluronic-adsorbed beads is much less defined, relative to bare beads. They appear much larger in diameter and have a wider size distribution.…”

Section: Afm Analysismentioning

confidence: 99%

Characterization of the molecular structure and mechanical properties of polymer surfaces and protein/polymer interfaces by sum frequency generation vibrational spectroscopy and atomic force microscopy

Koffas

2004

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Sum frequency generation (SFG) vibrational spectroscopy, atomic force microscopy (AFM), and other complementary surface-sensitive techniques have been used to study the surface molecular structure and surface mechanical behavior of biologically-relevant polymer systems. SFG and AFM have emerged as powerful analytical tools to deduce structure/property relationships, in situ, for polymers at air, liquid and solid interfaces. The experiments described in this dissertation have been performed to understand how polymer surface properties are linked to polymer bulk composition, substrate hydrophobicity, changes in the ambient environment (e.g., humidity and temperature), or the adsorption of macromolecules. The correlation of spectroscopic and mechanical data by SFG and AFM can become a powerful methodology to study and engineer materials with tailored surface properties. 2The overarching theme of this research is the interrogation of systems of increasing structural complexity, which allows us to extend conclusions made on simpler model systems. We begin by systematically describing the surface molecular composition and mechanical properties of polymers, copolymers, and blends having simple linear architectures. Subsequent chapters focus on networked hydrogel materials used as soft contact lenses and the adsorption of protein and surfactant at the polymer/liquid interface.The power of SFG is immediately demonstrated in experiments which identify the chemical parameters that influence the molecular composition and ordering of a polymer chain's side groups at the polymer/air and polymer/liquid interfaces. In general, side groups with increasingly greater hydrophobic character will be more surface active in air.Larger side groups impose steric restrictions, thus they will tend to be more randomly ordered than smaller hydrophobic groups. If exposed to a hydrophilic environment, such as water, the polymer chain will attempt to orient more of its hydrophilic groups to the surface in order to minimize the total surface energy.With an understanding of the structural and environmental parameters which govern polymer surface structure, SFG is then used to explore the effects of surface hydrophobicity and solvent polarity on the orientation and ordering of amphiphilic neutral polymers adsorbed at the solid/liquid interface. SFG spectra show that poly(propylene glycol) (PPG) and poly(ethylene glycol) (PEG) adsorb with their hydrophobic moieties preferentially oriented toward hydrophobic polystyrene surfaces.These same moieties, however, disorder when adsorbed onto a hydrophilic silica/water interface. Water is identified as a critical factor for mediating the orientation and ordering of hydrophobic moieties in polymers adsorbed at hydrophobic interfaces. 3The role of bulk water content and water vapor, as they influence hydrogel surface structure and mechanics, continues to be explored in the next series of experiments. A method was developed to probe the surface viscoelastic properties of hydroxylethyl methacrylate (HEMA) base...

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Protein hydration from water oxygen-17 magnetic relaxation

Cited by 202 publications

References 1 publication

Protein Hydration Dynamics in Aqueous Solution: A Comparison of Bovine Pancreatic Trypsin Inhibitor and Ubiquitin by Oxygen-17 Spin Relaxation Dispersion

Protein Hydration Dynamics in Aqueous Solution: A Comparison of Bovine Pancreatic Trypsin Inhibitor and Ubiquitin by Oxygen-17 Spin Relaxation Dispersion

Biological water at the protein surface: Dynamical solvation probed directly with femtosecond resolution

Characterization of the molecular structure and mechanical properties of polymer surfaces and protein/polymer interfaces by sum frequency generation vibrational spectroscopy and atomic force microscopy

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