Biomedical subjects

M F Mesleh

Publications and source records attributed to M F Mesleh.

3 recordsLinked to original sources

PubMed2005

NMR experiments on aligned samples of membrane proteins.

NMR methods can be used to determine the structures of membrane proteins. Lipids can be chosen so that protein-containing micelles, bicelles, or bilayers are available as samples. All three types of samples can be aligned weakly or strongly, depending on their rotational correlation time. Solution NMR methods can be used with weakly aligned micelle and small bicelle samples. Solid-state NMR methods can be used with mechanically aligned bilayer and magnetically aligned bicelle samples.

Electrophoresis, Polyacrylamide Gel↗

PubMed2003

Myristoylation as a general method for immobilization and alignment of soluble proteins for solid-state NMR structural studies.

N-terminal myristoylation of the immunoglobulin-binding domain of protein G (GB1) from group G Streptococcus provides the means to bind the protein to aligned phospholipid bilayers for solid-state NMR structural studies. The myristoylated protein is immobilized by its interactions with bilayers, and the sample alignment enables orientationally dependent 15N chemical shifts and 1H-15N-dipolar couplings to be measured. Spectra calculated for the average solution NMR structure of the protein at various orientations with respect to the magnetic field direction were compared to the experimental spectrum. The best fit identified the orientation of the myristoylated protein on the lipid bilayers, and demonstrated that the protein adopts a similar structure in both its myristoylated and non-myristoylated forms, and that the structure is not grossly distorted by its interaction with the phosholipid bilayer surface or by its location in the restricted aqueous space between bilayer leaflets. The protein is oriented such that its charged sides face the phosphatidylcholine headgroups of the lipids with the single amphiphilic helix running parallel to the bilayer surface.

Bacterial Proteins↗

PubMed2002

Structure determination of membrane proteins by NMR spectroscopy.

Current strategies for determining the structures of membrane proteins in lipid environments by NMR spectroscopy rely on the anisotropy of nuclear spin interactions, which are experimentally accessible through experiments performed on weakly and completely aligned samples. Importantly, the anisotropy of nuclear spin interactions results in a mapping of structure to the resonance frequencies and splittings observed in NMR spectra. Distinctive wheel-like patterns are observed in two-dimensional 1H-15N heteronuclear dipolar/15N chemical shift PISEMA (polarization inversion spin-exchange at the magic angle) spectra of helical membrane proteins in highly aligned lipid bilayer samples. One-dimensional dipolar waves are an extension of two-dimensional PISA (polarity index slant angle) wheels that map protein structures in NMR spectra of both weakly and completely aligned samples. Dipolar waves describe the periodic wave-like variations of the magnitudes of the heteronuclear dipolar couplings as a function of residue number in the absence of chemical shift effects. Since weakly aligned samples of proteins display these same effects, primarily as residual dipolar couplings, in solution NMR spectra, this represents a convergence of solid-state and solution NMR approaches to structure determination.

Animals↗