1975-32-2Relevant articles and documents
Induced allostery in the directed evolution of an enantioselective Baeyer-Villiger monooxygenase
Wu, Sheng,Acevedo, Juan Pablo,Reetz, Manfred T.
experimental part, p. 2775 - 2780 (2010/10/03)
The molecular basis of allosteric effects, known to be caused by an effector docking to an enzyme at a site distal from the binding pocket, has been studied recently by applying directed evolution. Here, we utilize laboratory evolution in a different way, namely to induce allostery by introducing appropriate distal mutations that cause domain movements with concomitant reshaping of the binding pocket in the absence of an effector. To test this concept, the thermostable Baeyer-Villiger monooxygenase, phenylacetone monooxygenase (PAMO), was chosen as the enzyme to be employed in asymmetric Baeyer-Villiger reactions of substrates that are not accepted by the wild type. By using the known X-ray structure of PAMO, a decision was made regarding an appropriate site at which saturation mutagenesis is most likely to generate mutants capable of inducing allostery without any effector compound being present. After screening only 400 transformants, a double mutant was discovered that catalyzes the asymmetric oxidative kinetic resolution of a set of structurally different 2-substituted cyclohexanone derivatives as well as the desymmetrization of three different 4-substituted cyclohexanones, all with high enantioselectivity. Molecular dynamics (MD) simulations and covariance maps unveiled the origin of increased substrate scope as being due to allostery. Large domain movements occur that expose and reshape the binding pocket. This type of focused library production, aimed at inducing significant allosteric effects, is a viable alternative to traditional approaches to designed directed evolution that address the binding site directly.
Copper-catalyzed preparation of ketones bearing a stereogenic center in α position
Soorukram, Darunee,Knochel, Paul
, p. 3686 - 3689 (2008/02/12)
A highly enantioselective synthesis of α-alkylated and -arylated ketones can be achieved by using a reaction sequence consisting of a stereoselective anti-SN2′ allylic substitution in the presence of CuCN·2LiCl following by the oxidation of an intermediate cycloalkenyl lithium species using (Me3SiO)2 or (MeO) 3B/NaBO3·4H2O. (Chemical Equation Presented).
Enantioface-differentiating protonation with chiral γ-hydroxyselenoxides
Takahashi, Tamiko,Nakao, Naoki,Koizumi, Toru
, p. 3293 - 3308 (2007/10/03)
Enantioface-differentiating protonation of a chiral metal enolates of α-alkylcarbonyl compounds 7 has been developed using chiral γ-hydroxyselenoxides 1 as a proton source. Reaction of zinc bromide enolates of 2-benzyl- and 2-n-propylcyclohexanones with (S(Se))-1e gave (S)-2-benzylcyclohexanone 7a and (R)-2-n-propylcyclohexanone 7c in high enantiomeric excess, respectively. Intramolecular hydrogen bonding of the selenoxide 1, chelation effects between 1 and metal enolate, and 2-exo-hydroxy-10-bornyl-framework could contribute to this asymmetric induction.
