De novo helical peptides as target sequences for a specific, fluorogenic protein labelling strategy.

New methods are needed to selectively label proteins in a manner that minimally perturbs their structures and functions. We have developed a 'small molecule'-based labelling technique that relies on the use of dimaleimide fluorogens that react with a target peptide sequence that presents appropriately spaced, solvent-exposed Cys residues. The thiol addition reaction between target sequence and dimaleimide fluorogen restores the latent fluorescence of the latter and results in the covalent fluorescent labelling of the protein of interest (J.

6-hydroxy to 6'''-amino tethered ring-to-ring macrocyclic aminoglycosides as probes for APH(3')-IIIa kinase.

Based on molecular modeling and available X-ray structure data on aminoglycosides complexed with a bacterial ribosomal surrogate or with a kinase, two analogues of paromomycin were prepared by tethering the 6-OH and the 6'''-NH(2) group with a five-carbon bridge. Only one of two possible hydroxyl groups was phosphorylated by the kinase. The application of ring closure metathesis is presented for the first time to construct bridged macrocyclic analogues in the aminoglycoside series.