Catalytic, theoretical, and biological investigation of an enzyme mimic model.

Gülcihan Gülseren

doi:10.3906/kim-2104-51

Abstract

Artificial catalyst studies were always stayed at the kinetics investigation level, in this work bioactivity of designed catalyst were shown by the induction of biomineralization of the cells, indicating the possible use of enzyme mimics for biological applications. The development of artificial enzymes is a continuous quest for the development of tailored catalysts with improved activity and stability. Understanding the catalytic mechanism is a replaceable step for catalytic studies and artificial enzyme mimics provide an alternative way for catalysis and a better understanding of catalytic pathways at the same time. Here we designed an artificial catalyst model by decorating peptide nanofibers with a covalently conjugated catalytic triad sequence. Owing to the self-assembling nature of the peptide amphiphiles, multiple action units can be presented on the surface for enhanced catalytic performance. The designed catalyst has shown an enzyme-like kinetics profile with a significant substrate affinity. The cooperative action in between catalytic triad amino acids has shown improved catalytic activity in comparison to only the histidine-containing control group. Histidine is an irreplaceable contributor to catalytic action and this is an additional reason for control group selection. This new method based on the self-assembly of covalently conjugated action units offers a new platform for enzyme investigations and their further applications. Artificial catalyst studies always stayed at the kinetics investigation level, in this work bioactivity of the designed catalyst was shown by the induction of biomineralization of the cells, indicating the possible use of enzyme mimics for biological applications.

Highlights

Our increasing demand for natural like biomaterial has resulted in a growing interest in the development of artificial catalysts [1]
The secondary structure formation of peptide amphiphiles was evaluated by circular dichroism analysis, beta-sheet specific peaks were obtained around 205 and 220 nm indicating the hydrogen bond formation among the peptide monomers (Figure 1)
The secondary structure formation was indicated via Fourier transform infrared (FTIR) spectroscopy as another identification technique, the spectra obtained from freeze dried peptide nanofibers showed an amide peak at around 1630 cm−1 accompanied by a broad band at 1680 cm–1, indicating sheet-like secondary structure formation of nanostructures [27]

Summary

Introduction

Our increasing demand for natural like biomaterial has resulted in a growing interest in the development of artificial catalysts [1]. The catalytic triad is a most common sequence found in various enzyme types (i.e. hydrolases and esterases) [15] ü and this set of coordinated amino acids, histidine/serine/aspartic acid (DHS), is frequently used in catalytic sites of artificial mimics [16]. The proposed structure in our new design will form the basis for nanofiber-based catalytic activity as well as the function.

Results

Conclusion