Potent inhibitors of fucosyltransferases, and glycosyltransferases in general, have been elusive due to the inherent barriers surrounding the family of glycosyltransfer reactions. The problems of weak substrate affinity and low catalytic proficiency of fucosyltransferase was offset by recruiting additional binding features, in this case hydrophobic interactions, to produce a high affinity inhibitor, 24, with Ki = 62 nM. The molecule was identified from a GDP-triazole library of 85 compounds, which was produced by the Cu(I)-catalyzed [2 + 3] cycloaddition reaction between azide and acetylene reactants, followed by in situ screening without product isolation.

Target‐guided synthesis: Rather than making and screening thousands of compounds for lead discovery, in situ click chemistry employs the biological target itself to assemble its inhibitors by selectively binding and interconnecting reagents within the confines of its binding sites. Subnanomolar inhibitors of carbonic anhydrase II were produced by the enzyme from simple azide and acetylene precursors (see picture).

Das Protein als Reaktor: Statt Tausende von Verbindungen zu synthetisieren und zu testen, um eine Leitstruktur zu finden, nutzt die In‐situ‐Click‐Chemie das biologische Zielmolekül selbst zum Inhibitoraufbau: Die Reagentien werden selektiv in den Bindungsstellen des Zielmoleküls gebunden und verknüpft. Von der Carboanhydrase II wurden so subnanomolare Inhibitoren aus einfachen Azid‐ und Acetylenvorstufen synthetisiert (siehe Bild).

The anthrax lethal factor (LF), a Zn-dependent endopeptidase, is considered the dominant virulence factor of anthrax. Because pharmacological inhibition of the catalytic activity of LF is considered a plausible mechanism for preventing the lethality of anthrax, a high-throughput screening experiment based on LF-catalyzed cleavage of a fluorescent substrate was performed to identify novel inhibitors of LF. The RNA-targeting antibiotics, neomycin B and some synthetic dimeric aminoglycosides, were found to be nanomolar active-site inhibitors of LF.

Defence against bioterrorism: Recent events have created an urgent need for therapeutic strategies to treat anthrax, an infectious disease caused by the toxigenic bacterium Bacillus anthracis. A new class of aminoglycosides (see picture) are powerful inhibitors under physiological conditions of the anthrax lethal factor, which has a major role in the disease, and function simultaneously as antibiotics against B. anthracis.