6M8F

Engineered sperm whale myoglobin-based carbene transferase

Summary for 6M8F

• Entry DOI: 10.2210/pdb6m8f/pdb
• Related PRD ID: PRD_900003
• Descriptor: Myoglobin, beta-D-fructofuranose-(2-1)-alpha-D-glucopyranose, SULFATE ION, ... (5 entities in total)
• Functional Keywords: metalloprotein, myoglobin, carbene transferase, cyclopropanation, heme, transferase
• Biological source: Physeter catodon (Sperm whale)
• Total number of polymer chains: 1
• Total formula weight: 18545.07

Authors

Bacik, J.P.,Ando, N.,Fasan, R. (deposition date: 2018-08-21, release date: 2019-01-23, Last modification date: 2023-10-11)

Primary citation

Tinoco, A.,Wei, Y.,Bacik, J.P.,Carminati, D.M.,Moore, E.J.,Ando, N.,Zhang, Y.,Fasan, R.
Origin of high stereocontrol in olefin cyclopropanation catalyzed by an engineered carbene transferase.
Acs Catalysis, 9:1514-1524, 2019

PubMed Abstract: Recent advances in metalloprotein engineering have led to the development of a myoglobin-based catalyst, Mb(H64V,V68A), capable of promoting the cyclopropanation of vinylarenes with high efficiency and high diastereo- and enantioselectivity. Whereas many enzymes evolved in nature often exhibit catalytic proficiency and exquisite stereoselectivity, how these features are achieved for a non-natural reaction has remained unclear. In this work, the structural determinants responsible for chiral induction and high stereocontrol in Mb(H64V,V68A)-catalyzed cyclopropanation were investigated via a combination of crystallographic, computational (DFT), and structure-activity analyses. Our results show the importance of steric complementarity and non-covalent interactions involving first-sphere active site residues, heme-carbene, and the olefin substrate, in dictating the stereochemical outcome of the cyclopropanation reaction. High stereocontrol is achieved through two major mechanisms. First, by enforcing a specific conformation of the heme-bound carbene within the active site. Second, by controlling the geometry of attack of the olefin on the carbene via steric occlusion, attractive van der Waals forces and protein-mediated π-π interactions with the olefin substrate. These insights could be leveraged to expand the substrate scope of the myoglobin-based cyclopropanation catalyst toward non-activated olefins and to increase its cyclopropanation activity in the presence of a bulky α-diazo-ester. This work sheds first light into the origin of enzyme-catalyzed enantioselective cyclopropanation, furnishing a mechanistic framework for both understanding the reactivity of current systems and guiding the future development of biological catalysts for this class of synthetically important, abiotic transformations.

PubMed: 31134138
DOI: 10.1021/acscatal.8b04073

Experimental method

X-RAY DIFFRACTION (1.1 Å)