3WI8

Crystal structure of horse heart myoglobin reconstituted with manganese porphycene

Summary for 3WI8

• Entry DOI: 10.2210/pdb3wi8/pdb
• Descriptor: Myoglobin, PORPHYCENE CONTAINING MN, SULFATE ION, ... (4 entities in total)
• Functional Keywords: globin fold, oxygen transport, muscles
• Biological source: Equus caballus (domestic horse,equine)
• Total number of polymer chains: 1
• Total formula weight: 17795.25

Authors

Mizohata, E.,Oohora, K.,Kihira, Y.,Inoue, T.,Hayashi, T. (deposition date: 2013-09-09, release date: 2014-03-26, Last modification date: 2024-03-20)

Primary citation

Oohora, K.,Kihira, Y.,Mizohata, E.,Inoue, T.,Hayashi, T.
C(sp3)-H bond hydroxylation catalyzed by myoglobin reconstituted with manganese porphycene.
J.Am.Chem.Soc., 135:17282-17285, 2013

PubMed Abstract: Myoglobin reconstituted with manganese porphycene was prepared in an effort to generate a new biocatalyst and was characterized by spectroscopic techniques. The X-ray crystal structure of the reconstituted protein reveals that the artificial cofactor is located in the intrinsic heme-binding site with weak ligation by His93. Interestingly, the reconstituted protein catalyzes the H2O2-dependent hydroxylation of ethylbenzene to yield 1-phenylethanol as a single product with a turnover number of 13 at 25 °C and pH 8.5. Native myoglobin and other modified myoglobins do not catalyze C-H hydroxylation of alkanes. Isotope effect experiments yield KIE values of 2.4 and 6.1 for ethylbenzene and toluene, respectively. Kinetic data, log kobs versus BDE(C(sp(3))-H) for ethylbenzene, toluene, and cyclohexane, indicate a linear relationship with a negative slope. These findings clearly indicate that the reaction occurs via a rate-determining step that involves hydrogen-atom abstraction by a Mn(O) species and a subsequent rebound hydroxylation process which is similar to the reaction mechanism of cytochrome P450.

PubMed: 24191678
DOI: 10.1021/ja409404k

Experimental method

X-RAY DIFFRACTION (2.2 Å)