Click chemistry in solving protein 3-D structures

Long live protein chemistry! Early days saw the use of cross-linking reagents such as DCC to lock in spatially adjacent amino groups within proteins. Nowadays the progress of mass spectrometry and proteomics has greatly enhanced the ability to study protein 3-D structures and protein interactions. Here a group of researchers went to click chemistry for additional assistance. Anal Chem 2012, 2662

See the scheme:

Cholesterol & protein studied by Click chemistry

Chemical Communications Received 31st October 2010, Accepted 21st December 2010 DOI: 10.1039/c0cc04710d

Tate and coworkers from Imperial College London reported the bioorthogonal click chemistry of a fluorescent alkyne probe with azido-modified post-translationally cholesterylated proteins - in living cells. The design is shown in the drawing. This enables rapid multiplexed fluorescence detection and affinity labelling of protein cholesterylation. This method, in comparison with the current radiolabeling, offers safety, speed, sensitivity, and flexibility. It may allow the observation of protein cholesterylation over space and time using fluorescence microscopy.

In more complex and challenging environment, click chemistry has found application and success, only due to its extremely high efficiency and orthogonality.
                                         

Enzyme-linked click chemistry assay for GOAT

cat-ELCCA, enzyme-linked click chemistry assay, was developed by Janda Group for high througput assay of GOAT, Ghrelin O-Acetyl transferase. The methodology is depicted in the drawing. The following chemistries are elegantly combined for the assay: biotin-straptavidin binding, CuAAC click chemistry, HRP catalysis, O-acetyltransferase catalysis, and fluorogenic reaction.

The method should accelerate identification of inhibitors for GOAT, which activates ghrelin by esterification with a C-8 fatty acid unit. It intimately relates to the effort of seeking agents that lower ghrelin levels as obesity or diabetes treatments.

Much like the cat-ELISA assays in immunology, cat-ELCCA, should find applications in other acyltransferases.

Angew. Chem. Int. Ed. 2010, 9630.
                                                     

Post-assembly click chemistry in DNA origami structure

Kurt Vesterager Gothelf et al, Nature Nanotechnology, 2010, Vol 5, 200. First published online on February 28th.

Seeman and others have turned DNA nanostructures or DNA origami into a fascinating science with extraordinary structural features and with developing applications and potentials in many fields. This publication demonstrates that chemical reactions with single molecules can be performed and imaged at a local position on a DNA origami scaffold by atomic force microscopy via direct detection of Streptavidin anchored onto the nanostructure by biotins.


The biotins are incorporated into the DNA origami via acetylene-azide click chemistry and others. The high yields and chemoselectivities achieved in these reactions demonstrate the feasibility of post-assembly chemical modification of DNA nanostructures. This report opens the door for many applications in biotechnology and materials science since the design and formation of DNA origami is getting mature enough and now post-assembly reactions allow workers to reliably conjugate / insert the molecules of interest in a spatially controlled manner.

One of the many good uses of Huisgen–Sharpless–Meldal copper(I)-catalysed click chemistry.