Caseoperoxidase, mixed β-casein-SDS-hemin-imidazole complex: a nano artificial enzyme.

PubMed ID: 25562503

Author(s): Moosavi-Movahedi Z, Gharibi H, Hadi-Alijanvand H, Akbarzadeh M, Esmaili M, Atri MS, Sefidbakht Y, Bohlooli M, Nazari K, Javadian S, Hong J, Saboury AA, Sheibani N, Moosavi-Movahedi AA. Caseoperoxidase, mixed β-casein-SDS-hemin-imidazole complex: a nano artificial enzyme. J Biomol Struct Dyn. 2015;33(12):2619-32. doi: 10.1080/07391102.2014.1003196. Epub 2015 Feb 11. PMID 25562503

Journal: Journal Of Biomolecular Structure & Dynamics, Volume 33, Issue 12, 2015

A novel peroxidase-like artificial enzyme, named “caseoperoxidase”, was biomimetically designed using a nano artificial amino acid apo-protein hydrophobic pocket. This four-component nano artificial enzyme containing heme-imidazole-β-casein-SDS exhibited high activity growth and k(cat) performance toward the native horseradish peroxidase demonstrated by the steady state kinetics using UV-vis spectrophotometry. The hydrophobicity and secondary structure of the caseoperoxidase were studied by ANS fluorescence and circular dichroism spectroscopy. Camel β-casein (Cβ-casein) was selected as an appropriate apo-protein for the heme active site because of its innate flexibility and exalted hydrophobicity. This selection was confirmed by homology modeling method. Heme docking into the newly obtained Cβ-casein structure indicated one heme was mainly incorporated with Cβ-casein. The presence of a main electrostatic site for the active site in the Cβ-casein was also confirmed by experimental methods through Wyman binding potential and isothermal titration calorimetry. The existence of Cβ-casein protein in this biocatalyst lowered the suicide inactivation and provided a suitable protective role for the heme active-site. Additional experiments confirmed the retention of caseoperoxidase structure and function as an artificial enzyme.