Luminescent Host Molecules for Multisite Recognition of Polyphosphate Anions

The search for new drugs often begins with high-throughput screening of lead compounds followed by determination of mode of action of the potential drug and measurements of selectivity and potency. Many drugs act by inhibiting enzyme activity, therefore, to increase confidence in the selection of lead drug compounds it is crucial that pharmaceutical companies have robust, affordable assays to measure enzyme activity accurately. Enzymes that consume and produce nucleoside polyphosphate anions represent a major target in cancer drug discovery. This will enable the best drug candidates to be identified before they enter expensive animal and human testing.

The majority of existing enzyme assays require expensive, unstable antibodies or chemically modified reagents, which are time consuming to prepare and require special care in handling. The high cost of these reagents and time required to validate the assays places a significant strain on the drug development process. In addition, these assays are restricted to single 'end-point' measurements, which limits our understanding of the mode of action of a new drug. This increases the risk of a drug candidate passing the early development stages, only to fail at a later, more expensive stage. In order to increase productivity earlier in the drug discovery process, a low-cost method for real-time monitoring of enzyme activity is urgently needed.

The aim of this project is to develop molecular probes that bind reversibly to specific nucleoside polyphosphate anions (e.g. adenosine diphosphate) that are produced during pharmaceutically important enzyme reactions. Upon binding to the anion, the probe will provide a luminescent signal that precisely indicates the activity of the enzyme in real-time. The probes will be used to directly measure the production of polyphosphate anions common to several important enzyme classes (kinases, GTPases, glycosyltransferases), eliminating the need for expensive antibodies or chemically modified reagents. The proposed molecular probes have enormous potential to reduce the cost and time required to conduct high-throughput screening assays. They will provide a vital step towards the rapid, accurate determination of enzyme kinetics and mechanism. This will enable better selection and validation of new drug candidates at an early stage in drug discovery, reducing effort pursuing compounds destined to fail in the more lengthy and costly phases of animal and human testing.

The long-term goal of this project is for the proposed molecular probes to be adopted by pharmaceutical companies to identify and validate new potent enzyme inhibitors.

Economy: Our research will lead to significant improvements in enzyme assay technology, which currently relies upon expensive, unstable antibodies, labelled substrates, or access to expensive instrumentation (e.g. Perkin Elmer Labchip EZ Reader). The costs of modern one-day drug screen of 50,000 compounds can cost £60,000 in assay reagents alone. Replacing antibodies with low-cost molecular probes that are compatible with standard plate readers will have a positive impact on the UK economy. Pharmaceutical companies utilising our technology will make significant savings in instrumentation and assay components (antibodies, labelled reagents), providing a more efficient mechanism for screening and identifying new drug compounds. The ability to report enzyme activity in real-time will enable the accurate determination of enzyme kinetics and thus a better understanding of inhibition mechanism, contributing towards a more informed drug development paradigm. Without such assays, the risk is that a drug candidate will pass the early development stages, only to fail at a later, more costly development phase.

Society: The proposed research will contribute towards more effective treatments of a range of diseases, which will have a knock-on effect to societal impact. If pharmaceutical companies can produce drugs more cheaply, then the savings will be passed on to the end users, such as the National Health System, eventually leading to more affordable healthcare in a system that is under increased governmental pressure to make savings.

Environment: The molecular probes described in this proposal can be tailored to detect different anions and adapted readily for applications in environmental monitoring organisations and in real-time industrial quality control. For example, probes capable of quantifying harmful organophosphorous anions (e.g. pesticides, herbicides) in water supplies will facilitate better management of agricultural resources to reduce anionic pollutants in watercourses, leading to improved consumer health.

This project will be an excellent opportunity to showcase how physical sciences can address healthcare and societal problems. More effective treatments of diseases and affordable healthcare are areas that capture public interest and support. This will enable us to further engage the general public and young audiences in the concept of developing chemical tools to advance drug discovery research, raising awareness of the power of synthetic chemistry and the physical sciences.