Biotinylated anisomycin: a comparison of classical and "click" chemistry approaches.

Two approaches to the synthesis of biotinylated derivatives of the stress-activated protein kinase (SAPK) pathway activator anisomycin have been investigated. Attachment of the biotin moiety to the central core was achieved either through the use of a classical displacement reaction on alpha-halo carbonyl derivatives of biotin or through a copper(I)-catalyzed 1,3-dipolar Huisgen cycloaddition ("click") coupling of biotinylated azides to propargyl-marked analogues of anisomycin. In each case, the resultant N-linked molecular probes were found to be active in SAPK pathway immunoblot assays, while their O-linked counterparts were inactive. However, in sharp contrast to the classical coupling approach which results in low coupling yields, the aqueous "click" coupling process was found to deliver high yields of biotinylated probes, making it the conjugation method of choice. A survey of the available methods for the addition of a propargyl marker onto a range of chemical functionalities strongly suggests that this copper(I)-catalyzed 1,3-dipolar Huisgen cycloaddition approach to biotinylation may be generally applied.

A sensitized europium complex generated by micromolar concentrations of copper(I): toward the detection of copper(I) in biology.

Formation of a luminescent device by the Huisgen 1,3-dipolar cycloaddition reaction between a Eu(III) complex and dansyl azide is reported. This reaction is catalyzed by a common biological copper(I) complex [GS--Cu(I)], and the resultant copper(I) catalytic sensor shows a 10-fold enhancement of europium luminescence emission.

Effect on pKa of metal-bound water molecules in lanthanide ion-induced cyclen "cavities".

[reaction: see text] The macrocyclic cyclen conjugates 1-4 were synthesized with the aim of forming lanthanide ion-based macrocyclic conjugates possessing deep cavities, formed upon complexation to various lanthanide ions. These complexes all possess metal-bound water molecules, where the pKa of the water molecules depends on the nature of the cavity.

Rapid hydrolytic cleavage of the mRNA model compound HPNP by glycine based macrocyclic lanthanide ribonuclease mimics.

The lanthanide ion based macrocyclic complexes 1.Ln mimic the hydrophobic nature of ribonucleases, where the lanthanide ions induce the formation of a hydrophobic cavity for 1, giving rise to a large order of magnitude enhancement in the hydrolytic cleavage of HPNP.