CYCLODEXTRINS AS TEMPLATES FOR THE PRESENTATION OF PROTEASE INHIBITORS

Mono(6-succinylamido-6-deoxy)-beta-cyclodex was synthesized by classic al carbohydrate chemistry and used as a template mono-functionalized w ith the Linear, fully flexible 4C-spacer carboxylate for covalent link age of the calpain inhibitor leucyl-leucyl-norleucinal. Spectroscopic analyses of the conjugate do not support a self-inclusion of part of t he hydrophobic peptide tail, but confirm its intra- or intermolecular interaction with the template moiety that leads to full water solubili ty. The inhibitory potency of the beta-cyclodextrin/peptide aldehyde c onstruct was compared with that of the parent Ac-Leu-Leu-Me-H against cathepsin B and calpain, Despite the large size of the template the in hibition of cathepsin B was only slightly reduced in full agreement wi th the X-ray structure of this enzyme which shows full accessibility o f the S-subsites, For this enzyme the 4C-spacer is apparently sufficie nt to guarantee optimal interaction of the peptide tail with the bindi ng cleft. Conversely, for mu-calpain a significantly decreased inhibit ory potency was obtained with the conjugate suggesting steric interfer ence of the template in the binding process, These results show that t he beneficial properties of the cyclodextrin template can be retained in conjugates with bioactive peptides if attention is paid to optimize in each case the size and nature of the spacer for optimal recognitio n of the grafted biomolecule.