Use patents: cases from research results

Baseclick produces a wide variety of click chemistry optimised products and services, ranging from labelling kits and catalysts to solvents and reagents. The advantages of the product include the broad range of application possibilities, high yields and quick and easy reaction conditions using readily available and inexpensive reagents. Baseclick holds patents worldwide for these applications, which can be used to:

• detect, control and analyse cell proliferation in vitro and in vivo
• label DNA and RNA for the preparation of, for example, FISH probes
  
• label nucleic acids and other biochemical molecules

Backed by sound expertise, ongoing research and a good business strategy, Baseclick is now a well-established enterprise with revenue in the two-digit million range. Its path to success was, however, not always straightforward, as it encountered major difficulties when an unexpected event put the project’s viability at stake and forced the researchers to reconsider their chances of achieving their aims.

In 2003, a group led by Thomas Carell, Professor of Chemistry at Munich’s Ludwig Maximilians University (LMU), and supported by a grant from BASF started to research the use of the “click chemistry” discovered by Professor Sharpless of the Scripps Institute, to modify nucleic acids. Together with his PhD students Gramlich, Gierlich and Burley, he began work on optimising the click chemistry reactions for biomolecules. Soon, the group was able to show that most existing DNA labelling methods could be replaced by click chemistry to provide a new labelling system that was fast, reliable, highly specific and high-yielding.

The group demonstrated that, in theory, every base in a DNA strand could be labelled by a functional group. In 2005, this co-operative venture between the LMU and BASF led to the filing of a patent application entitled “New labelling strategies for the sensitive detection of analytes”. The group’s findings were then published in the specialist journal Organic Letters (J. Gierlich, G. A. Burley, P. M. E. Gramlich, D. M. Hammond, T. Carell, “Click Chemistry as a Reliable Method for the High-Density Postsynthetic Functionalization of Alkyne-Modified DNA”, Org Lett. 2006, 8, 3639-3642).

Technical Background

Since the advent of DNA decryption, a great deal of research has focused on improving our understanding of how it works, among others for medical purposes. For example, to identify disease-related mutations of the DNA, certain locations of the DNA strands are marked for further analysis. This marking is usually done with fluorescent labels that are attached at different locations of the DNA strand. The techniques for this labelling have been improved constantly over the last 20 years.

Professor Barry Sharpless, Nobel Prize laureate, discovered the copper mediated azido-alkine cyclo-addition (CuAAC) reaction in 2001. Sharpless named this chemical reaction type “click chemistry”. It allows the addition of fragments to existing molecules to which fluorescent elements can be added. This reaction was simple, clean and generic.

Professor Thomas Carell, founder of Baseclick, adapted this method to the modification of biomolecules, since neither azide nor terminal alkyne functional groups are generally present in natural systems. Alkyne-modified DNA nucleobases are functionalised by the addition of the corresponding labelled azide (e.g. fluorescent-dye-azides) using the CuAAC reaction. This results in the obtention of labelled DNA, and allows tracing of the DNA modifications. Professor Carell and his team further developed the method for nucleic acid modification by adding ligands specific for copper (copper stabilising agents) in the reaction, as copper ions damage DNA. The ligands bind to free copper and protect the biomolecules from degradation (see Fig. 1).