This research aligns with the strategic priorities of the Medical Research Council (MRC) as it aims to investigate the gaps in knowledge and infrastructure needs to deliver new insights and benefits to human health. As stated in their strategic plan one research priority is “living a long and healthy lifestyle” and in doing this is understanding molecular datasets and diseases by using biological indicators and being able to target treatments. The Molecular, Cellular and Medicine Board (MCMB) is keen to understand dynamic biological systems and this research proposal requires understanding the dynamics of the KMO enzyme and application of this allows development of inhibitors to match the drug site and gaining an understanding of  their mechanism of action. This research uses analytical tools and systems approaches to understand complex and dynamic biology different scales. These approaches will be used to develop cell therapies and cell engineering systems biology for drug target discovery and development. This will help us understand the mechanisms of the enzyme and allow us to develop new drugs that target the enzyme.

Inhibition of KMO has been identified as a potentially beneficial therapeutic strategy in diseases including Huntington’s disease, Alzheimer’s disease and acute pancreatitis. There is therefore a need to develop potent inhibitors of KMO that do not act as effectors. In this work we aim to detect the flavin movement during inhibition by selected inhibitors. This will allow us to investigate the effects of the substituents. Crystallisation of the KMO enzyme with the inhibitors will allow us to understand their binding and important interactions between the inhibitor and the enzyme which will give us insight for developing more potent inhibitors which could be used clinically.

Crystal structures of KMO have been obtained but there is not thorough characterisation of residues in the active site has been completed. We aim to investigate the binding of NADPH to KMO and will try to trap it and characterise the binding site. The information in this work should complement previously obtained structures and by the use of binding simulations we should be able to characterise the binding site.

Tryptophan is an essential amino acid in mammals. 95% of tryptophan metabolism occurs via the kynurenine pathway (KP). The KP uses the enzyme kynurenine monooxygenase (KMO) to catalyse the conversion of L-kynurenine (L-Kyn) to 3-hydrokynurenine (3-HK) in the presence of nicotinamide adenosine dinucleotide phosphate (NADPH) and molecular oxygen. Further conversion of 3-HK produces quinolinic acid (QUIN). The metabolites 3-HK and QUIN have biological activity and imbalances in their levels are associated with neurological disorders such as Alzheimer’s and Huntington’s disease. 3-HK generates unstable, toxic molecules that stimulate neuronal cell death. QUIN also generates unstable, toxic molecules that cause neuronal damage in the central nervous system by activating the N-methyl-D-aspartate (NMDA) receptors. The KP has also been associated in the development of other brain disorders such as schizophrenia, bipolar disease, cancers and autoimmune disorders. The activity of KMO has significant influence over the resultant ratio of neurotoxic to neuroprotective metabolites therefore its inhibition is a leading strategy for normalising the KP pathway and a shifting it towards neuroprotection in neurodegenerative diseases.

KMO undergoes a conformation change when L-Kyn binds. This conformational change frees space in the enzyme for NADPH to bind. The flavin gets changed and 3-HK is produced alongside H₂O₂. It is proposed that conformational changes via interactions between L-Kyn and the loop of the flavin trigger flavin reduction in KMO. These interactions do not occur in some inhibitors and NADPH cannot bind which means the flavin is not reduced and no H₂O₂ is produced. The investigation of the binding site of NADPH and of flavin dynamics would be useful for structure-based drug design to stop the production of harmful metabolites and by-products.

The research aims to deliver improved drugs for neurodegenerative disorders (NDs) such as Alzheimer’s disease (AD). Currently there are around 30 million people worldwide suffering from AD; which is also the main cause of dementia. Drugs are available for the management of the symptoms of AD, however no treatments that halt the disease’s progression or onset are available.

AD is estimated to be the disease with the biggest cost of lost years to disability (11%). Dementia costs the UK £26.3 billion a year and AD costs the UK £17 billion a year. The total number of people with dementia in the UK is predicted to double in the next 25 years; increasing costs to £50 billion. Studies show that ND costs the NHS more than heart diseases and cancer combined. The identification of an effective treatment for AD and other NDs could cut these expenditures worldwide.

Biotechnology and pharmaceutical companies with research and development and/or commercial interests also stand to benefit. It will have important implications for the potential development of a new therapeutic strategy in AD. The work will form the basis of developing treatments for those who have developed or are likely to develop the disease. Significant breakthroughs in KMO-based therapies will encourage participation in the clinical trials.

Understanding the mechanistic underpinning of the disease will assist in the development of treatments. The discovery of underling therapeutic targets in one ND offers hope for researchers and patients alike. This is particularly the case with the kynurenine pathway as it has been implicated in the pathogenesis of several NDs. The neuronal loss during neurodegeneration is irreversible therefore therapies need to target the pre-degenerative disease state. Research in Alzheimer’s, for which there is an enzyme that will inhibit the production of neurotoxic metabolites may form the basis of the development of preventative treatments in other NDs.