Novel heterocyclic ligands for the lipid kinase PI4KIIIβ : a chemical biology approach

Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2020
Thesis identifier
  • T16606
Person Identifier (Local)
  • 201658683
Qualification Level
Qualification Name
Department, School or Faculty
  • This thesis is divided into two parts. Part One investigates the physicochemical properties, in particular the thermodynamic solubility, of 6,5-bicyclic heterocycles. The heterocycle with the best balance of properties was taken forward as a scaffold for Part Two of the research, where lipid kinase PI4KIIIβ was targeted with an electrophilic, covalent warhead. Part One of this thesis details the synthesis of a range of nitrogen containing 6,5- bicyclic heterocyclic cores shown below which are common scaffolds in medicinal chemistry. The physicochemical properties of these compounds were measured, and a comparison of the data was carried out. Crystalline solids were obtained where possible to give a more robust comparison of the thermodynamic solubility. Various parameters such as pKa, melting point and solubility, were investigated. [see illustration in thesis] The biological target for the compounds prepared was lipid kinase PI4KIIIβ which is responsible for the synthesis of PI4P (phosphatidylinositol 4-phosphate), the most abundant phosphoinositide in eukaryotic cells, that plays a critical role in a number of pathological processes, one being a key mediator for viral replication. There is significant interest in targeting PI4KIIIβ because viruses are able to hijack the cell’s machinery for replication. This has led to an interest in PI4KIIIβ as being a potential target to treat diseases such as hepatitis C, human rhinovirus infection and also cancer cell proliferation. Part Two of the thesis builds upon the results of Part One, where the core with the best balance of activity against PI4KIIIβ and physicochemical properties was taken forwards. This was appended with different electrophilic warheads to initially target covalent modification of the conserved lysine in the active site of PI4KIIIβ. A range of novel fluorosulfate based inhibitors were synthesised and their stability to buffers and reactivity to amino acids were investigated. In addition to measuring enzymatic potency a long incubation cellular assay was also carried out, and the enhanced potency indicated the possibility of a non-reversible binding event. To determine the potential for covalent modification, the compounds were profiled by protein mass spectrometry to identify adducts. The onset of inhibition was measured and the rate constants for the reversible and irreversible binding events were determined. [see illustration in thesis] The success of the fluorosulfate covalent inhibitors targeting PI4KIIIβ led to the exploration of the first in-house non-cysteine targeted covalent fragment library. Data on the solubility from Part One of the thesis was used to aid the design of PI4KIIIβ fragment fluorosulfate molecules to selectively target PI4KIIIβ and validate the concept of a fluorosulfate fragment library. Finally, a robust and high throughput synthetic procedure for synthesising a first generation of a fluorosulfate fragment library was established and the fragment set was screened against several protein targets.
Advisor / supervisor
  • Tomkinson, Nicholas
Resource Type
  • Previously held under moratorium in the Chemistry department (GSK) from 31st March 2020 until 2nd June 2023.
Embargo Note
  • The digital version of this thesis is restricted to Strathclyde users only until 31st March 2025.