Screen, Design and Enzymatic Activity Determination of Artificial Microperoxidases

Peroxidase activity greatly impacts the maintenance of free radical homeostasis, and can prevent or treat diseases related to free radicals. Microperoxidase-11(MP-11) is created via hydrolysis of cytochrome c iron-porphyrin complexes. In these complexes, the heme iron is penta-coordinate with histidine and exhibits excellent antioxidant activity when decomposing hydrogen peroxide. In this study, we screened the Ph.D.-7 and Ph.D.-12 phage display peptide libraries and obtained ten small peptide ligands of deuterohemin(the vinyl groups of oxidized heme). Among these polypeptides, DhHP-7P1, 12P1, 12P2 and 12P6 have good enzymatic activity compared with MP-11, and exhibit activities up to 50% of MP-11. Based on the screened sequences, we designed a series of artificial microperoxidases and determined that a higher peroxidase activity could be achieved with an enzymatic active site containing a second site of histidine residue spaced between two arginine residues with an interval of two amino acids(Dh-XHRXXR).