112 research outputs found
Inverting Small Molecule-Protein Recognition by the Fluorine Gauche Effect: Selectivity Regulated by Multiple H→F Bioisosterism
Fluorinated motifs have a venerable history in drug
discovery, but as C(sp3
)@F-rich 3D scaffolds appear with
increasing frequency, the effect of multiple bioisosteric changes
on molecular recognition requires elucidation. Herein we
demonstrate that installation of a 1,3,5-stereotriad, in the
substrate for a commonly used lipase from Pseudomonas
fluorescens does not inhibit recognition, but inverts stereoselectivity. This provides facile access to optically active,
stereochemically well-defined organofluorine compounds (up
to 98% ee). Whilst orthogonal recognition is observed with
fluorine, the trend does not hold for the corresponding
chlorinated substrates or mixed halogens. This phenomenon
can be placed on a structural basis by considering the
stereoelectronic gauche effect inherent to F@C@C@X systems
(s!s*). Docking reveals that this change in selectivity (H
versus F) with a common lipase results from inversion in the
orientation of the bound substrate being processed as a consequence of conformation. This contrasts with the stereochemical interpretation of the biogenetic isoprene rule, whereby
product divergence from a common starting material is also
a consequence of conformation, albeit enforced by two discrete
enzymes
Ueber die Ernährung der Italiener
UEBER DIE ERNÄHRUNG DER ITALIENER
Ueber die Ernährung der Italiener (99) (-
- …