Dataset Information

Hydrophobic hydration of amphipathic peptides.

ABSTRACT: Biomolecular surfaces and interfaces are commonly found with apolar character. The hydrophobic effect thus plays a crucial role in processes involving association with biomolecular surfaces in the cellular environment. By computer simulation, we compared the hydrogen bonding structures and energetics of the proximal hydration shells of the monomer and dimer from a recent study of an extrinsic membrane peptide, melittin. The two peptides were studied in their amphipathic alpha-helical forms, which possess extended hydrophobic surfaces characterized by different topography. The topography of the peptide-water interface was found to be critical in determining the enthalpic nature of hydrophobic hydration. This topographical dependence has far-reaching implications in the regulation of bioactivities in the presence of amphipathicity. This result also engenders reconsideration of the validity of using free energy parameters that depend solely on the chemical nature of constituent moieties in characterizing hydrophobic hydration of proteins and biomolecules in general.

SUBMITTER: Cheng YK

PROVIDER: S-EPMC1300152 | biostudies-other | 1999 Apr

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Hydrophobic hydration of amphipathic peptides.

Cheng Y K YK Sheu W S WS Rossky P J PJ

Biophysical journal 19990401 4

Biomolecular surfaces and interfaces are commonly found with apolar character. The hydrophobic effect thus plays a crucial role in processes involving association with biomolecular surfaces in the cellular environment. By computer simulation, we compared the hydrogen bonding structures and energetics of the proximal hydration shells of the monomer and dimer from a recent study of an extrinsic membrane peptide, melittin. The two peptides were studied in their amphipathic alpha-helical forms, whic ...[more]

PMID: 10096874

Similar Datasets

Project description:The evolution of bonded restorations has undergone great progress over several decades. Nonetheless, life spans of bonded restorations are limited mainly because of the eventual incidence of recurrent caries. Over time, water and waterborne agents (acids, enzymes) degrade the components of the dentin/restoration interface, allowing bacterial colonization and dentin reinfection at the margins of the restoration. We developed a 2-tier protective technology consisting of priming/coating dentin with amphipathic and antimicrobial peptides (AAMPs) to obtain hydrophobic/water-repellent and antibiofilm dentin-resisting recurrent caries around bonded restorations. We tested a series of AAMPs to assess their structure-function relationships as well as the effects of different dentin-conditioning methods on the structural features of AAMP-coated dentin. We found relation between the secondary structure of AAMPs (high portion of β-sheet), the antimicrobial potency of AAMPs, and the AAMPs' ability to form hydrophobic coatings on dentin. We also determined that AAMPs had preferential adsorption on the mineral phase of dentin, which suggested that peptides arrange their cationic and hydrophilic motifs in direct contact with the negatively charged minerals in the hydrophilic dentin. These results led us to explore different dentin-conditioning methods that would increase the mineral/collagen ratio and their effect on AAMP immobilization. We innovatively imaged the spatial distribution of the AAMPs in relation to the dentinal tubules and collagen network using a minimally invasive multimodal imaging technique: multiphoton-second harmonic generation. Using multiphoton-second harmonic generation imaging, we determined that partial deproteinization of dentin increased the amount of immobilized AAMPs as compared with the total etched dentin at the dentin surface and extended deeply around dentinal tubules. Last, we analyzed the release rate of AAMPs from dentin coatings in artificial saliva to predict their stability in the clinical setting. In conclusion, priming dentin with AAMPs is a versatile new approach with potential to fortify the otherwise vulnerable adhesive-based interfaces.

Project description:Hydrophobic molecules are by definition difficult to hydrate. Previous studies in the area of hydrophobic hydration have therefore often relied on using amphiphilic molecules where the hydrophilic part of a molecule enabled the solubility in liquid water. Here, we show that the hydrophobic adamantane (C10H16) molecule can be fully hydrated through vapour codeposition with water onto a cryogenic substrate at 80 K resulting in the matrix isolation of adamantane in amorphous ice. Using neutron diffraction in combination with the isotopic substitution method and the empirical potential structure refinement technique, we find that the first hydration shell of adamantane is well structured consisting of a hydrogen-bonded cage of 28 water molecules that is also found in cubic structure II clathrate hydrates. The four hexagonal faces of the 51264 cage are situated above the four methine (CH) groups of adamantane whereas the methylene (CH2) groups are positioned below the edges of two adjoining pentagonal faces. The oxygen atoms of the 28 water molecules can be categorised on the basis of symmetry equivalences as twelve A, twelve B and four C oxygens. The water molecules of the first hydration shell display orientations consistent with those expected for a clathrate-hydrate-type cage, but also unfavourable ones with respect to the hydrogen bonding between the water molecules. Annealing the samples at 140 K, which is just below the crystallisation temperature of the matrix, removes the unfavourable orientations and leads to a slight increase in the structural order of the first hydration shell. The very closest water molecules display a tendency for their dipole moments to point towards the adamantane which is attributed to steric effects. Other than this, no significant polarisation effects are observed which is consistent with weak interactions between adamantane and the amorphous ice matrix. FT-IR spectroscopy shows that the incorporation of adamantane into amorphous ice leads to a weakening of the hydrogen bonds. In summary, the matrix-isolation of the highly symmetric adamantane in amorphous ice provides an interesting test case for hydrophobic hydration. Studying the structure and spectroscopic properties of water at the interface with hydrophobic hydrocarbons is also relevant for astrophysical environments, such as comets or the interstellar medium, where amorphous ice and hydrocarbons have been shown to coexist in large quantities.

Dataset Information

Hydrophobic hydration of amphipathic peptides.

Publications

Hydrophobic hydration of amphipathic peptides.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets