| Popis: |
Enzymes are among the most effective catalysts known so far both in terms of their efficiency as well as selectivity. They can achieve rate accelerations of up to a factor of 1011 and more, and sometimes react exclusively with only one single stereoisomer of a substrate if required. Enzymes make use of various different mechanisms of catalysis such as transition-state binding, acid–base catalysis, nucleophilic catalysis, entropic control of reactions, and so on, with roughly half the known enzymes using metal ions while the other half solely relies on organic functional groups. Owing to these fascinating features of enzymes, chemists have tried to mimic enzymes early on developing artificial enzyme models. Over the years, a multitude of functional artificial enzyme models for very different types and classes of enzymes were developed, some closely mimicking the mode of action of their natural counterparts whereas others just adopt some general features found in enzymes. We briefly discuss some selected examples of artificial enzyme mimics in this review. Of course, the following examples are only a few picked out of a great variety. We do not attempt to provide a complete overview in respect to enzymes that are mimicked or models that were developed, but rather focus on the different approaches and concepts used to imitate an enzyme. The choice of examples is purely reflecting our personal preferences and is not implied to indicate that any work not mentioned is less interesting. We have arranged the examples of enzyme mimics and presented roughly according to their increasing chemical and structural complexity, starting with simple metal complexes (Section 1), then discussing cyclodextrin and related enzyme mimics (Section 2) before focusing on polymer- and dendrimer-derived systems (Section 3). Miniproteins and oligopeptides with defined structures are then discussed (Section 4) before we end with a brief description of catalytic antibodies (Section 5). Keywords: enzyme mimics; bioorganic chemistry; catalysis; metal complexes; cyclodextrins; miniproteins; catalytic antibodies; polymer- and dendrimer-based enzyme mimics |
