Cyclodextrins as templates for the presentation of protease inhibitors

Abstract

Mono(6-succinylamido-6-deoxy)-13-cyclodextrin was synthesized by classical carbohydrate chemistry and used as a template mono-functionalized with the linear, fully flexible 4C-spacer carboxylate for covalent linkage of the calpain inhibitor leucyl-leucyl-norleucinal. Spectroscopic analyses of the conjugate do not support a self-inclusion of part of the hydrophobic peptide tail, but confirm its intra-or intermolecular interaction with the template moiety that leads to full water solubility. The inhibitory potency of the ~-cyclodextrin/peptide aldehyde construct was compared with that of the parent Ac-Leu-Leu-Nle-H against cathepsin B and calpain. Despite the large size of the template the inhibition of cathepsin B was only slightly reduced in full agreement with the X-ray structure of this enzyme which shows full accessibility of the S-subsites. For this enzyme the 4C-spacer is apparently sufficient to guarantee optimal interaction of the peptide tail with the binding cleft. Conversely, for gcalpain a significantly decreased inhibitory potency was obtained with the conjugate suggesting steric interference of the template in the binding process. These results show that the 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 recognition of the grafted biomolecule.

A novel synthetic luteinizing hormone-releasing hormone (LHRH) analogue coupled with modified β-cyclodextrin: Insight into its intramolecular interactions

“…For example, there are certain activated carboxylic derivatives which show enhanced reactivity and selectivity towards the amino than the hydroxyl group. In addition, in literature this synthetic methodology has been successfully applied in other examples where peptides were attached to CDs [19][20][21][22][23][24][25][26][27][28]. Another point of consideration was the short distance between the CD and the peptide if the amino CD derivative is directly attached to glycine.…”

Inhibition of cysteine proteases by peptides containing aziridine-2,3-dicarboxylic acid building blocks

“…The selective epoxide derived inhibitors of cathepsin B like CA030 (1) that bind to the S1Ј and S2Ј pocket of this enzyme in a substrate-like orientation are significantly more potent in their (R, R) configuration 30 whereas the opposite is found for the nonselective EP-475 like compounds (e.g., 2) that interact in an antisubstrate direction with the nonprimed binding sites. 31 A convergence of the inhibition constants was found for a chimeric epoxide 30 that combines peptide sequences for the S1Ј/S2Ј specificity of cathepsin B (Leu-Pro) with the inhibiting procathepsin B sequence Leu-Gly-Gly for which an interaction with the nonprimed sites is known. The stereospecificities of the three types of aziridines were investigated by comparing two different diastereomeric pairs for each type of inhibitor.…”

Carbohydrates in peptide and protein design

“…Several different types of covalent peptidecyclodextrin conjugates have been reported. Among the first were publications by Parrot-Lopez et al on the preparation of cyclodextrins singly substituted with amino acids [67][68][69] or peptides, 70 by Vecchio 76 and coworkers in 1992, Å kerfeldt and DeGrado 81 in 1994, Hanessian 79 and coworkers in 1995, Moroder 83 and coworkers and Stoddart 80 in separate publications in 1996. cyclodextrins have been used extensively in the de novo design of potential, biomimetic catalysts. However, in general, these designs do not incorporate peptides as such, with a few exceptions.…”

“…The unspecific binding events make -cyclodextrins promising as candidates for conjugation. These studies were preceded by work in the same group on the amidation of mono-(6-deoxy-6-succinoylamino-)--cyclodextrin with the protease inhibitor, H-Leu-Leu-Nle-H. 83,84 They have also reported the crystal structure of human -tryptase as a 1:2 complex with -cyclodextrin difunctionalized with short peptide inhibitors. 83,84 This proved the concept of cyclodextrin as scaffolds to control the distance-geometry in the display of ligands for interaction with multimeric protein complexes.…”