Biomedical subjects

O Spiga

Publications and source records attributed to O Spiga.

3 recordsLinked to original sources

PubMed2004

On the dynamics of water molecules at the protein solute interfaces.

Proteins, with the large variety of chemical groups they present at their molecular surface, are a class of molecules which can be very informative on most of the possible solute-solvent interactions. Hen egg white lysozyme has been used as a probe to investigate the complex solvent dynamics occurring at the protein surface, by analysing the results obtained from Nuclear Magnetic Resonance, X-ray diffractometry and Molecular Dynamics simulations. A consistent overall picture for the dynamics of water molecules close to the protein is obtained, suggesting that a rapid exchange occurs, in a picosecond timescale, among all the possible hydration surface sites both in solution and the solid state, excluding the possibility that solvent molecules can form liquid-crystal-like supramolecular adducts, which have been proposed as a molecular basis of 'memory of water'.

Animals↗

PubMed2001

NMR studies of protein surface accessibility.

Characterization of protein surface accessibility represents a new frontier of structural biology. A surface accessibility investigation for two structurally well-defined proteins, tendamistat and bovine pancreatic trypsin inhibitor, is performed here by a combined analysis of water-protein Overhauser effects and paramagnetic perturbation profiles induced by the soluble spin-label 4-hydroxy-2,2,6,6-tetramethyl-piperidine-1-oxyl on NMR spectra. This approach seems to be reliable not only for distinguishing between buried and exposed residues but also for finding molecular locations where a network of more ordered waters covers the protein surface. From the presented set of data, an overall picture of the surface accessibility of the two proteins can be inferred. Detailed knowledge of protein accessibility can form the basis for successful design of mutants with increased activity and/or greater specificity.

Aprotinin↗

PubMed2001

Probing the surface of a sweet protein: NMR study of MNEI with a paramagnetic probe.

The design of safe sweeteners is very important for people who are affected by diabetes, hyperlipemia, and caries and other diseases that are linked to the consumption of sugars. Sweet proteins, which are found in several tropical plants, are many times sweeter than sucrose on a molar basis. A good understanding of their structure-function relationship can complement traditional SAR studies on small molecular weight sweeteners and thus help in the design of safe sweeteners. However, there is virtually no sequence homology and very little structural similarity among known sweet proteins. Studies on mutants of monellin, the best characterized of sweet proteins, proved not decisive in the localization of the main interaction points of monellin with its receptor. Accordingly, we resorted to an unbiased approach to restrict the search of likely areas of interaction on the surface of a typical sweet protein. It has been recently shown that an accurate survey of the surface of proteins by appropriate paramagnetic probes may locate interaction points on protein surface. Here we report the survey of the surface of MNEI, a single chain monellin, by means of a paramagnetic probe, and a direct assessment of bound water based on an application of ePHOGSY, an NMR experiment that is ideally suited to detect interactions of small ligands to a protein. Detailed surface mapping reveals the presence, on the surface of MNEI, of interaction points that include residues previously predicted by ELISA tests and by mutagenesis.

Magnetic Resonance Spectroscopy↗