50 research outputs found
Detailed Ab Initio First-Principles Study of the Magnetic Anisotropy in a Family of Trigonal Pyramidal Iron(II) Pyrrolide Complexes
A gonadotropin-releasing hormone type neuropeptide with a high affinity binding site for copper(ii) and nickel(ii).
In vertebrates gonadotropin-releasing hormone I (GnRH-I) is a key regulator of reproductive development and function. The receptor-binding activity of human GnRH-I can be modified by the presence of divalent copper. Thus, copper binding to N-terminal amino acids in GnRH-I induces structural changes that influence receptor interactions and downstream intracellular signalling cascades. It is not known if copper-binding is restricted to human GnRH-I or if it is also a feature of GnRH-type peptides that have been identified in other taxa. To investigate this, we have characterised copper binding to a recently discovered GnRH-type peptide from the starfish Asterias rubens (ArGnRH). Using a range of spectroscopic and biophysical techniques we show that this peptide can bind copper(ii) and nickel(ii). Copper(ii) is bound in a square-planar, high-affinity (Kd ∼ 10-12 M) site incorporating four nitrogen donor atoms from a histidine imidazole group, two amides and the N-terminal amine group. The ArGnRH copper affinity and geometry are quite different to GnRH-I suggesting the copper sites have evolved to suit the environment the peptides are exposed to. By comparing the copper binding sites in ArGnRH and human GnRH-I and conducting a phylogenetic analysis of GnRH-type peptide sequences from a range of species, we predict that copper-binding is an evolutionarily ancient feature of GnRH-type peptides that has been retained, modified or lost in different lineages
Quatre lettres inédites d'Ange Goudar au marquis de Sade
Ange Goudar : Four unpublished letters to the Marquis de Sade, presented by Maurice Lever.
Sade met Pierre-Ange Goudar, writer and adventurer, in 1775 during his flight to Italy after the "little girls" affair. An exchange of letters followed ; four of them, from the Sade family archives, are published here. Goudar expresses his opinions of Rome, Naples and Florence, his reflections on Cardinal Bernis and the Count of Saint-Germain, and speaks about his wife Sarah and his own writings. These unpublished pages reveal a hitherto totally unknown literary friendship between the author of Justine and another libertine called Goudar.Lever Maurice. Quatre lettres inédites d'Ange Goudar au marquis de Sade. In: Dix-huitième Siècle, n°23, 1991. Physiologie et médecine. pp. 223-232
Introduction : Au seuil du XVIIe siècle
Lever Maurice. Introduction : Au seuil du XVIIe siècle. In: Littératures classiques, n°15, octobre 1991. Romanciers du XVIIe siècle. pp. 9-13