The First Example of an RNA Urea Synthase: Selection through the Enzyme Active Site of Human Neutrophile Elastase

RNA catalysts : In vitro selection from a random library of RNA sequences gave RNA urea synthases able to utilize tripeptides as substrates (see scheme; HNE, human neutrophile elastase). The tripeptide substrates were mechanism‐based protease suicide substrates. Stereoselection of serine protease tripeptide phosphonate inhibitors was achieved by RNA catalysis. The RNA urea synthases showed a high degree of diastereoselectivity for the most potent protease suicide inhibitor.