The present invention is based on the finding that the cis/trans
isomerisation of secondary amide peptide bonds in oligo- and polypeptides
can be catalytically promoted. This catalysis is effected by enzymes
which are hereinafter called "secondary amide peptide bond cis/trans
isomerases (APIases). It can be assumed that the APIase activity plays a
central role in a number of pathophysiological processes. Thus, the
invention relates to pharmaceutical compositions comprising substances
which inhibit APIase activity.