Human carbonic anhydrase II : a novel scaffold for artificial metalloenzymes

The development of efficient biocatalysts for industry remains a challenge. Over the past decade, the group of Professor Thomas R. Ward (University of Basel, Switzerland) has developed various artificial metalloenzymes for enantioselective catalysis. For this purpose, a biotinylated organometallic catalyst is incorporated in (Strept)avidin, thereby providing a hybrid catalyst that displays attractive features, reminiscent of both chemo- and biocatalysts.
Relying on knowledge acquired within the group, the main objective of my reasearch was to rationally design and study a novel class of artificial metalloenzymes centered on an alternative biomolecular scaffold: human Carbonic Anhydrase II (hCA II). The interest in hCA II is motivated by the possibility to use this protein as a target, because it is overexpressed in various forms of cancers. This feature may be exploited to accumulate a catalytic drug in cells requiring therapeutic action. A library of ruthenium piano-stool complex bearing a sulfonamide anchor was designed in silico, synthesized and tested as organometallic hCA II inhibitor.
An additional second recognition motif was subsequently introduced to further fine-tune the binding affinity of the metal complex for the hCA II. In parallel with these synthetic efforts, we developed widely applicable force field parameters amenable to molecular dynamics simulations of hCA II-inhibitor interactions. These were experimentaly validated and used to predict the affinity of fluorinated arylsulfonamide inhibitors for hCA II.
Based on computational results, a second generation of inhibitors with improved binding affinities for wild-type hCA II (10 nM) were designed in silico. Coupled to a second recognition element, which ensured precise localization of catalytic metals within the hCA II binding pocket, a well-defined chiral environment was tailored to provide a favourable environment for enantioselective catalysis. A chemogenetic optimization strategy (i.e. genetic variation of the hCA II combined with chemical fine-tuning of the piano-stool moiety) allowed for improving the catalytic performance of the artificial metalloenzyme for the reduction of prochiral imines.
During my PhD thesis, I gained expertize in the in-silico design, synthesis and biophysical characterization of organometallic inhibitors and their interaction with a model protein: human Carbonic Anhydrase II. The multidisciplinary environment provided in the group of Professor Thomas R. Ward gave me a unique opportunity to collaborate on a daily basis with molecular biologists, computational chemists, protein crystallographers etc.