Peptide-cleaving catalyst selective for melanin-concentrating hormone: oxidative decarboxylation of N-terminal aspartate catalyzed by Co(III)cyclen

Abstract

To provide a firm basis for the new paradigm of drug discovery based on catalysts for oxidative cleavage of N-terminal aspartate (Asp) residues of oligopeptides, oligopeptide-cleaving catalysts were searched by using melanin-concentrating hormone (MCH) as the substrate. MCH is a target for designing drugs to reduce obesity. Catalyst candidates containing the Co(III) complex of cyclen as the catalytic center were prepared by multicomponent condensation reactions. From three kinds of chemical libraries containing about 19,000 catalyst candidates, one compound was identified as the MCH-cleaving catalyst. On incubation with the catalyst, the N-terminal Asp residue of MCH was converted to the pyruvate residue by oxidative decarboxylation. Detailed kinetics analysis revealed the catalytic nature of the action of the catalyst. In addition, the kinetics data indicated that MCH can be cleaved with half-lives of 3 h or less with submicromolar catalyst concentrations if the structure of the catalyst is further improved.

Theoretical Analysis and Prediction of Catalysts for Oxidative Decarboxylation of Melanin-Concentrating Hormone

“…9 The dependence of k o and C o for the catalytic activity of B was measured at pH 8.0 and the results are illustrated in Figure 3. The kinetic data of Figure 3 can be analyzed in terms of the Michaelis-Menten scheme as performed previously 9 with the MCH cleavage catalyzed by A. The linear dependence is consistent with very weak complexation between MCH and B (K m >> S o ).…”

“…, pseudo-first-order kinetic behavior is to be observed. 9 Since the concentration of MCH decreased slowly even in the absence of catalysts, 9 the background rate was subtracted to estimate pseudo-first-order rate constants (k o ). The pH dependence of k o measured at a fixed C o (Figure 2) showed that the optimum activity was manifested at pH 8.0.…”

“…Kinetic data were collected at 37 ± 0.1 o C. The concentration of MCH during the action of B was measured after tagging the N-terminal amino group of MCH with fluorescamine and quantifying the tagged MCH by HPLC as described previously. 9 NMR spectra were recorded with a Bruker DPX 300 MHz model. HPLC analysis was carried out with a 1100 series Agilent Technology HPLC.…”

“…[5][6][7][8] From chemical libraries containing about 19000 derivatives of Co(III)cyclen, only A was found to have catalytic activity for oxidative decarboxylation of the N-terminal Asp of MCH. 9 In view of the potential utility of the catalyst for oxidative decarboxylation of MCH as catalytic drugs for obesity, it is desirable to provide theoretical explanation for the activity of A and to discover other compounds possessing improved catalytic activity. For these purposes, we have carried out docking simulation for the complex formed between A and MCH and have synthesized a derivative of A on the basis of the results of the docking simulations.…”

Cleavage Agents for α-Synuclein

“…1,2,7,[11][12][13][14][15][16][17][18][19] The present study indicates that the target-selective artificial proteases may be especially effective for amyloidoses such as Alzheimer's disease, diabetes, Parkinson's disease, Huntington's disease, and mad cow's disease for which the conventional drugs targeting active sites of proteins cannot be designed.…”