Steven J. Collier

On the development of new biocatalytic processes for practical pharmaceutical synthesis.

Biocatalysis has established itself as a scalable and green technology for the production of a broad range of pharmaceutical APIs and intermediates. The number and scope of biocatalysts employed on large scale to deliver cost-advantaged and quality-advantaged processes to important substances continue to expand. This review discusses the recent developments in the field, including examples of processes leveraging hydrolases, reductases, transaminases, oxidases and other biocatalysts, focused on the preparation of important investigational and launched therapeutics. Biocatalysts recently discovered, and in some cases rediscovered, for the interesting chemistry they enable are likely to further substantiate the expansion of the biocatalysis field.

The role of distant mutations and allosteric regulation on LovD active site dynamics

Natural enzymes have evolved to perform their cellular functions under complex selective pressures, which often require their catalytic activities to be regulated by other proteins. We contrasted a natural enzyme, LovD, which acts on a protein-bound (LovF) acyl substrate, with a laboratory-generated variant that was transformed by directed evolution to accept instead a small free acyl thioester, and no longer requires the acyl carrier protein. The resulting 29-mutant variant is 1000-fold more efficient in the synthesis of the drug simvastatin than the wild-type LovD. This is the first non-patent report of the enzyme currently used for the manufacture of simvastatin, as well as the intermediate evolved variants. Crystal structures and microsecond molecular dynamics simulations revealed the mechanism by which the laboratory-generated mutations free LovD from dependence on protein-protein interactions. Mutations dramatically altered conformational dynamics of the catalytic residues, obviating the need for allosteric modulation by the acyl carrier LovF.

Baeyer–Villiger Monooxygenase-Mediated Synthesis of Esomeprazole As an Alternative for Kagan Sulfoxidation

A wild-type Baeyer-Villiger monooxygenase was engineered to overcome numerous liabilities in order to mediate a commercial oxidation of pyrmetazole to esomeprazole, using air as the terminal oxidant in an almost exclusively aqueous reaction matrix. The developed enzyme and process compares favorably to the incumbent Kagan inspired chemocatalytic oxidation, as esomeprazole was isolated in 87% yield, in >99% purity, with an enantiomeric excess of >99%.

Synthesis of Vibegron Enabled by a Ketoreductase Rationally Designed for High pH Dynamic Kinetic Reduction

Described here is an efficient stereoselective synthesis of vibegron enabled by an enzymatic dynamic kinetic reduction that proceeds in a high-pH environment. To overcome enzyme performance limitations under these conditions, a ketoreductase was evolved by a computationally and structurally aided strategy to increase cofactor stability through tighter binding.