Biocatalytic activity of methyl-modified microperoxidase-11 in transformation of nickel- and vanadium-porphyrins

Microperoxidase-11 (also known as MP-11) was chemically modified by boron trifluoride–methanol reagent to obtain methylated MP-11 (mMP-11). Porphyrin transformation capability of mMP-11 in a ternary solvent system was investigated by spectroscopic and kinetic techniques and compared with those of native MP-11. Methyl-modified MP-11 showed higher porphyrin transformation efficiency for synthetic nickel- and vanadium-porphyrins than native MP-11. Upon the chemical modification, the initial rates of porphyrin transformation in a solvent mixture of methylene chloride, methanol and water (up to 5%, v/v) were increased by 60.0-, 4.1-, 7.0- and 1.13-fold for VTPP (V-tetraphenyl porphyrin), VOEP (V-octaethyl porphyrin), NiTPP (Ni-tetraphenyl porphyrin) and NiOEP (Ni-octaethyl porphyrin), respectively. Modified MP-11 also exhibited a good degradation potential in the presence of kerosene (a crude oil fraction). In an organic solvent mixture containing kerosene (35%, v/v), mMp-11 in compared to unmodified MP-11 showed 46.0-, 2.1-, 14.1- and 3.1-times higher activity for VTPP, VOEP, NiTPP and NiOEP, respectively. Experimental data showed that concentration and type of organic hydroperoxides, temperature, and pH of the added water play significant roles on the porphyrin degradation.