Search

aa

aa

The development of radioisotopes of inorganic elements (as 68Ga(III) and 188Re(I)) has gained much interest in recent years for diagnostic and therapeutic application in nuclear medicine1. Small peptides are employed for complexing the radiometal in a biologically stable environment. They have some advantages: easy of synthesis and modification, tumorpenetrating ability and good biocompatibility2. Aim of the present work has been the interaction between Ga3+ ion with a bishistidine oligopeptide, PHIS (Fig.1) in aqueous solutions, by the following methods: Potentiometry, Spectrofluorimetry, FT−IR and 1HNMR Spectroscopy as also by Circular Dichroism. All the measurements have been investigated at 25 °C in 0.1 M NaClO4 media. Information on coordination sites are obtained with model molecule such as histidine (His). By processing the experimental data, it has been possible to obtain the complexation constants. Spectroscopy data are in agreement with the potentiometric measurement. 1H-NMR measurements conducted in H2O as solvent at different metal/ligand ratio indicate that imidazolic rings are involved in coordination with metal ions investigated .

Organometallic tricarbonyl complexes of Rhenium(I) and Technetium(I), fac−[M(H2O)3(CO)3]+ (M = Re, Tc), especially the aqueous complexes, have recently assumed an important role for diagnostic and therapeutic applications. In this regard, fac−[Re(H2O)3(CO)3]+ cation is readily conjugated to biomolecules which contain coordinating N, P, O, S atoms [1], where one or more water molecules can be replaced by ligands to obtain very stable d6 low−spin complexes [2]. Recently study has showed interaction between fac − [Re(H2O)3(CO)3]+ and histidine/imidazole molecule. Aim of this work is the study of the interaction among fac − [Re(H2O)3(CO)3]+ and some aminoacids that have been investigated using different instrumental techniques. Potentiometric titrations conducted with glass electrode in the pH range 2−10 estabilish that a complexation effect is observed. Information on complexes formation can be obtained also by spectrophotometric UV−VIS and fluorimetric measurements in solutions with different metal/ligand ratio.

APEH catalyses the removal of N-terminal acetylated amino acids from proteins destined to be degraded and is now recognized as a new therapeutic target for several diseases. New APEH inhibitors having triazole-based structures have been recently reported. On this basis we have screened a set of click-generated cyclic peptides, previously investigated for peptide conformational stability studies, as possible novel enzyme inhibitors. We have found a clicked peptide, NHB3.3, that inhibits APEH activity and structure–activity studies highlighted that APEH inhibition is mediated by the spatial organization of the triazole ring and by its orientation and distance from the peptide scaffold, whose structural integrity, in turn, also plays a relevant role. In conclusion, our findings confirm that 1,2,3 triazoles are privileged pharmacophores for specific serine protease inhibitors and provide structural insights exploitable for modulating their inhibition activity.