Synthetic Strategy to Prepare DOTA-Based Bifunctional Chelating Agent Ready to Bind Biomolecular Probes

Due to the continued interest in new bifunctional chelating agents (BFCA), we focused on the development of a convenient synthesis of 1,4,7,10-tetraazacyclododecane-1,4,7-tris(acetic acid)-10-butyrate mono (N-hydroxysuccinimidyl ester). It consists in the macrocycle DO3A derivatized with an aliphatic linker containing an active ester that requires selective and mild conditions to react with the targeting biomolecule. It is important to underlay the versatility of the obtained BFCA, which can be conjugated both to a biomolecule (protein, Fab fragment) or to a synthetic molecule. In a subsequent step, the developed chelator was successfully conjugated to a peptide sequence.     

A Drosophila melanogaster cell line tested for the presence of active NORs by silver staining

Silver staining was used to detect active NORs in a Drosophila melanogaster cell line (C1 82) characterized by dimorphic X chromosomes (XX_L), one of the two Xs showing a marked increase in heterochromatin where the nucleolar organizer (NO) is located. The Q-banding technique was used to determine the karyotype characteristics of the line. Ag-positive NORs appeared only on structurally changed X chromosomes (X_L), both in diploid and tetraploid cells, indicating that rRNA genes of X_L are more active or numerous than those on normal homologues. A possible relationship between NOR stainability, the presence of an increased heterochromatic portion and the selective advantage of XX_L cells, recurrent in numerous Drosophila female lines, is discussed.     

Lipidated peptides via post-synthetic thioalkylation promoted by molecular sieves

A thioalkylation procedure, which uses molecular sieves to promote the reaction, was exploited to provide peptides with useful functional groups (lipidic moieties), naturally occurring on proteins as post-translational modifications. The procedure was further implemented to synthesize tailor-made lipidated peptides, interesting tools to investigate biological processes involving their Ras parent proteins. Moreover, the one-pot preparation of multi-alkylated peptides confirms the versatility and flexibility of the employed methodology.