Regio‐ and Stereoselective Steroid Hydroxylation at C7 by Cytochrome P450 Monooxygenase Mutants
Aitao Li, Carlos G. Acevedo‐Rocha, Lorenzo D’Amore, Jinfeng Chen, Yaqin Peng, Marc Garcia‐Borràs, Chenghua Gao, Jinmei Zhu, Harry Rickerby, Sílvia Osuna, Jiahai Zhou, Manfred T. Reetz
Abstract
Abstract Steroidal C7β alcohols and their respective esters have shown significant promise as neuroprotective and anti‐inflammatory agents to treat chronic neuronal damage like stroke, brain trauma, and cerebral ischemia. Since C7 is spatially far away from any functional groups that could direct C−H activation, these transformations are not readily accessible using modern synthetic organic techniques. Reported here are P450‐BM3 mutants that catalyze the oxidative hydroxylation of six different steroids with pronounced C7 regioselectivities and β stereoselectivities, as well as high activities. These challenging transformations were achieved by a focused mutagenesis strategy and application of a novel technology for protein library construction based on DNA assembly and USER (Uracil‐Specific Excision Reagent) cloning. Upscaling reactions enabled the purification of the respective steroidal alcohols in moderate to excellent yields. The high‐resolution X‐ray structure and molecular dynamics simulations of the best mutant unveil the origin of regio‐ and stereoselectivity.