Biomedical subjects

D Di Maro

Publications and source records attributed to D Di Maro.

5 recordsLinked to original sources

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

Structural characterization and thermal stability of Notothenia coriiceps metallothionein.

Fish and mammalian metallothioneins (MTs) differ in the amino acid residues placed between their conserved cysteines. We have expressed the MT of an Antarctic fish, Notothenia coriiceps, and characterized it by means of multinuclear NMR spectroscopy. Overall, the architecture of the fish MT is very similar to that of mammalian MTs. However, NMR spectroscopy shows that the dynamic behaviour of the two domains is markedly different. With the aid of absorption and CD spectroscopies, we studied the conformational and electronic features of fish and mouse recombinant Cd-MT and the changes produced in these proteins by heating. When the temperature was increased from 20 to 90 degrees C, the Cd-thiolate chromophore absorbance at 254 nm of mouse MT was not modified up to 60 degrees C, whereas the absorbance of fish MT decreased significantly starting from 30 degrees C. The CD spectra also changed quite considerably with temperature, with a gradual decrease of the positive band at 260 nm that was more pronounced for fish than for mouse MT. The differential effect of temperature on fish and mouse MTs may reflect a different stability of metal-thiolate clusters of the two proteins. Such a conclusion is also corroborated by results showing differences in metal mobility between fish and mouse Zn-MT.

Amino Acid Sequence↗

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↗

PubMed2001

Carotid endarterectomy: a retrospective analysis. Microendarterectomy and transcranial Doppler ultrasound monitoring.

BACKGROUND: Analyses of the results obtained following our protocol for the surgical therapy of carotid artery stenosis is the aim of this study. METHODS: Ninety-one procedures were performed on 84 patients by the same surgical team. Indications for carotid endarterectomy (CEA) were 50-70% internal carotid artery (ICA) stenosis in 8% of the patients (100% symptomatic), 70-90% stenosis in 67% (64% symptomatic) and 90-99% ICA stenosis in 25% of our patients (33% symptomatic). Carotid shunt during arterial cross-clamp was only used in 4 cases (4.4%) following trans-cranial Doppler ultrasound (TCD) intraoperative monitoring findings. Operative microscope or surgical loupes were used for the complete removal of atheroma and the direct suture of the arteriotomy. Heparin was only antagonised in selected cases. RESULTS: No mortality and no permanent deficit related to ischemic events were present in our patients; a transient neurological deficit occurred in 1 case (1.1%). Two patients died (2.2%): 1 due to myocardial infarction and the second one to bronchopneumonia. Transient peripheral nerve deficits were noted in 2 cases. CONCLUSIONS: In order to reduce to a minimum ischemic risks during CEA, our preliminary experience advises microsurgical technique for the complete removal of the atheroma and suture, TCD evaluation of collateral reserve during cross-clamping, and the use of randomised multicenter studies guidelines for the selection of patients. More attention must also be given to postoperative care, since hemodynamic instability represents the main risk for our patients. Overnight intensive care unit (ICU) surveillance in all patients may help to avoid fatal complications.

Aged↗

PubMed1999

On the structural stability of a small bioactive peptide of potential use in biotechnology.

A tridecapeptide with the sequence CCEICCNPACFGC has been synthesized to reproduce the active moiety of a heat stable enterotoxin from Vibrio cholerae. The proton NMR analysis indicates, for the active synthetic fragment, a rigid secondary structure stabilised by three disulfide bridges. Such a rigid peptide, suitably detoxified and activated, could be a good candidate to be used as a carrier for linear bioactive peptides or other functional groups.

Biotechnology↗