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Updated: May 24, 2026

Site-Directed Mutagenesis for In Vitro and In Vivo Experiments Exemplified with RNA Interactions in Escherichia Coli
Published on: February 5, 2019
A single-site mutation (F429H) converts the enzyme CYP 2B4 into a heme oxygenase: a QM/MM study
Dandamudi Usharani1, Costantino Zazza, Wenzhen Lai
1Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
Abstract:
The intriguing deactivation of the cytochrome P450 (CYP) 2B4 enzyme induced by mutation of a single residue, Phe429 to His, is explored by quantum mechanical/molecular mechanical calculations of the O-OH bond activation of the (Fe(3+)OOH)(-) intermediate. It is found that the F429H mutant of CYP 2B4 undergoes homolytic instead of heterolytic O-OH bond cleavage. Thus, the mutant acquires the following characteristics of a heme oxygenase enzyme: (a) donation by His429 of an additional NH---S H-bond to the cysteine ligand combined with the presence of the substrate retards the heterolytic cleavage and gives rise to homolytic O-OH cleavage, and (b) the Thr302/water cluster orients nascent OH(•) and ensures efficient meso hydroxylation.
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