Metal Porphyrin (M-TPP) Complexed with Cysteine along with Hydrogel and Vesicle Scaffolds as Peroxidase and Catalase Nanozymes

Porphyrins can be widely considered as active site biocomplexes, while biomimetic-based synthetic metal porphyrins can be used as pseudo-enzymes. A system consisting of a metal porphyrin-cysteine complex and a “polyethylene glycol (PEG)” polymer or a mixture of the active surfactants "sodium dodecyl sulfate and dodecyl triethyl ammonium bromide (SDS/DTAB)" was used for native-chloroperoxidase model. Native chloroperoxidase could have the function of peroxidase, ie oxidation of substrates at different pHs. In the absence of a suitable substrate, chloroproxidase decomposes hydrogen peroxide indicating catalase activity. Metal-tetra (2-pyridyl) porphyrin (M-TPP), which is more resonant, is more potent than heme (as the native-enzyme active site) in its pseudo-peroxidase and catalase activity. Fe-TTP has the highest peroxidase activity among metal-porphyrins with central metals including iron (III), manganese (III) and zinc (II). The triple component: "Fe-TPP-cysteine-PEG" is most effective by reducing the Michaelis-Menten (KM) parameter. It is observed that the hydrophobicity of porphyrin increases with the change of the central metal to iron (III), manganese (III) and zinc (II), respectively. In this case, the hydrophobicity of the active site of the peroxidase-like nanozyme is a potential for more hydrophobic substrate (guaiacol) to enter the reaction cycle, resulting in greater Fe-TPP activity and efficiency than other M-TPP complexes. In the next step, to design the catalase biocatalyst, Mn-TPP has the highest catalase activity among other metal-porphyrins mentioned. The triple component: "Mn-TPP-cysteine-SDS/DTAB " is most effective by reducing the Michaelis-Menten (KM) parameter. Transmission electron microscopy shows M-TPP-cysteine-PEG nanozymes as multi-holes hydrogel colloids, compared to M-TPP-cysteine-SDS/DTAB single-hole vesicle catalyst, which indicates a higher efficiency through the higher specific surface area for effective treatment of peroxidase nanozyme with organic substrate.