Structure determination and by-product profile of the NK(2) receptor antagonist nepadutant, a bicyclic glycopeptide.

We have synthesized and fully characterized the NK(2) receptor antagonist nepadutant and its by-products using nuclear magnetic resonance (NMR) and restrained molecular dynamics. The agent consists of an active bicyclic hexapeptide combined with a sugar residue. Analysis of the high-performance liquid chromatogram and the mass spectroscopy spectra yields traces of three by-products with the same molecular weight as the main product. The conformation of the molecules in the bicyclic hexapeptide segment, the active region, is well defined, whereas the sugar moiety is disordered. For the peptide region of nepadutant and all of its by-products, the NMR observables can be described by a single backbone conformation, more specifically a betaI, betaII-turn arrangement. The active dipeptide unit Trp-Phe occupies the i+1 and i+2 position of a betaI-turn. The by-product profile is characterized by different forms of sugars which are caused mainly by isomerization in the process of ring opening.

Large-scale production of peptides using the solid-phase continuous flow method. Preparative synthesis of the novel tachykinin antagonist MEN 10627.

The large-scale solid-phase continuous flow synthesis of the bicyclic peptide MEN 10627, a new potent Neurokinin A receptor antagonist, is described using the Fmoc-polyamide method on both macrosorb 125 and Macrosorb 250 resin. A new synthesizer designed in-house was realized by assembling Whitey valves and Waters pump in order to allow small-scale (0.0001 mol; 1 x 10 cm Omnifit columns) synthetic studies which were strongly predictive of the conditions required for large-scale (0.01-0.10 mol; 3.6 or 5.9 x 46 cm Büchi columns) production, performed on the same apparatus.

Chymotrypsin-catalyzed fragment coupling synthesis of GnRH-analogs.

D-Xaa6-GnRH analogs (Xaa: Ala, Nal1), Phe, Ser(tBu), Trp) were prepared by chymotrypsin catalyzed 3 + 7 fragment coupling synthesis with conversion rates of the amino component in the range from 90.3 to 97.4%. For D-Phe6-GnRH the method was scaled up to production level.

Biospecific adsorbents on the basis of chloroformate-activated bead cellulose.

Carbohydrate-derived polymers are activated by the chloroformate N-chlorocarbonyloxy-5-norbornene-2.3-dicarboximide (ClCOONB). The advantages of this activation method are presented. The application of bead cellulose as adsorbent for biomedical and biotechnological purposes is demonstrated. Examples for immunoglobulin purification, streptavidin isolation, and biotransformation of porcine insulin are given.