Fusion of two proteins has become an important tool in biotechnology. Whereas biotechnological methods easily can produce C-terminal to N-terminal fused compounds, methods to couple two proteins to each of their C-termini are not easily accessible. Herein, peptides are used as models for larger proteins. A method is described exploiting the possibility to attach different reactive handles to their C-termini using a reaction catalyzed by the enzyme carboxypeptidase Y (CPY). It is possible to attach pairs of reaction handles which can react with each other to each of the peptides to be coupled. In a second step, the two modified peptides can be linked together by a chemical reaction, such as an oxime-forming reaction or a copper(I) catalyzed [2+3]-cycloaddition reaction of an azide with an alkyne.

A two-step strategy was used for the preparation of C-terminally PEGylated hGH-derivatives. In a first step a CPY-catalyzed transpeptidation was performed on hGH-Leu-Ala, introducing reaction handles, which were used in the second step for the ligation of PEG-moieties. Both oxime-ligation and copper(I) catalyzed [2+3]-cycloaddition reactions were used for the attachment of PEG-moieties. The biological data show a dependency of the potency of the hGH-derivatives on both size as well as shape of the PEG-group.

Benzo[b]thiophene-2-carboxamides and benzo[b]furan-2-carboxamides have been found to be antagonists on the human histamine-3-receptor, showing a Ki value of as low as 4 nM.

New imidazole-free H3 antagonists have been found in a series of cinnamic amides of (S)-(aminomethyl)pyrrolidines. The influence of the substituent on the aromatic moiety on the potency and the inhibition of three cytochrome P450 subtypes are also described.