Iron-Porphyrin/Cysteine/PEG as Pseudo-Chloroperoxidase Nanozyme

Porphyrins can be widely used as active-site biocomplexes, where biomimetic synthetic metal porphyrin is considered as being pseudo-enzyme. The system consisted of porphyrin-metal-cysteine (Cys) complex and PEG polymer or mixed SDS/DTAB surfactants has used to model native chloroperoxidase (CLP). Metal-tetra(2-pyridyl)porphyrins (M-TPP) as more potent than heme (native active-site) were designed and synthesized based on lowering Michaeilis-Menten parameter. Fe-TTP has the maximum CLP activity among central metal including iron(+3), manganese(+3) and zinc(+2). Triple-component: Fe-TPP/Cys/PEG, indicated most efficient "nanozyme" toward native CLP efficiency. It can be seen that porphyrin hydrophobicity varies by changing central metal, detected via Thioflavin T fluorescence method such as Fe(+3)> Mn(+3)> Zn(+2) attributed to charge transfer between pi-electron and central metal. Dynamic light scattering indicates that the addition of Fe-TPP/Cys, as PEG absorbent nucleus, causes nano-particle creation. Transmission electron microscopy illustrated multi-holes vesicular Fe-TPP/Cys/PEG nanozyme that causes more efficiency via higher specific surface area for substrate trap comparing one-hole vesicular Fe-TPP/Cys/SDS/DTAB biocatalyst. Presence of Fe-TPP/Cys active-site inside nanozyme was confirmed by UV-Visible spectroscopy as well as Circular dichroism. Differential scanning calorimetry indicates more single colloid structure for PEG nanozyme than attributed SDS/DTAB biocatalyst.