The r-mean curvature and rigidity of compact hypersurfaces in the Euclidean space

Annals of Global Analysis and Geometry - In this paper, we characterize round spheres in the Euclidean space under some suitable conditions on the r-mean curvature.     

Copper and iron interactions with angiotensin-converting enzyme inhibitors. A study by fast-atom bombardment tandem mass spectrometry

Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd.     

Weak exchange interaction supported by a biologically relevant long chemical bridge in a Cu-peptide model compound

The copper complex of the dipeptide L-alanyl-L-phenylalanine, catena-(L-alaninate-L-phenylalaninate-copper(II) monohydrate), identified as Cu(II)Ala-Phe, provides a convenient system to study a weak exchange interaction between unpaired spins transmitted through a biologically relevant long chemical bridge (18.34 A). In this complex, the copper ions are arranged in two symmetry-related anisotropic layers parallel to the ab plane at 13.17 A, separated by a double layer of water molecules. The equatorial-equatorial bridge considered as the most relevant path for exchange interactions between copper ions in neighbor layers contains 11 diamagnetic atoms (including three hydrogens), with two covalent amidate bridges plus three weak and moderate H bonds that go across the water layer. This interaction was studied using electron paramagnetic resonance in single-crystal samples, at 9.5 and 34.5 GHz. The measured magnitude of the interlayer interaction, |J3|/kB = 1.7(2) x 10(-3) K, is discussed in terms of values obtained for similar paths in other model compounds and in proteins. These results in model systems provide information that may be important in understanding biological functions at the molecular level.     

Synthesis, structural characterization and ex vivo biological properties of a new complex [Cu(propranolol)2]·2H2O, a potential beta-blocker

The synthesis and spectroscopic characterization (UV–Vis, IR, EPR) of a new copper complex with a beta-blocker propranolol (1-(isopropylamino)-3-(1-naphthyloxy)-2-propanol) are presented. Besides, the X-ray crystal structure of [Cu(propranolol)₂]·2H₂O is determined, showing two different copper ions, one coordinated through two S propranolol isomers and the other through two R isomers. The effect on the heart contraction force and on the heart rate plus the block of response to adrenaline of the complex and the free ligand, were studied. The effect of [Cu(propranolol)₂]·2H₂O on contractility was very similar to that of the free propranolol while the reduction on the heart rate is approximately 30% of the reduction obtained with the free ligand. This is an encouraging result since the search of new beta-blocker drugs that have lesser effect on heart rate is one of the important topics in cardiac pharmacology. The block of the response to adrenaline is at least similar for both ligand and complex.