Background – The post-genomic era has provided biologists with a wealth of information and –omic sequencing tools to further our understanding of fundamental biology and disease. However, it is still exceedingly difficult to interrogate biological processes where the link between gene and protein expression is decoupled. A pertinent exemplar of this is changes in the glycosylation state between healthy and cancerous cells presented on the cell surface. An emerging tool used to interrogate these changes is the metabolic incorporation of ‘chemical reporters’ within a target biomolecule and access to highly specific ‘bio-orthogonal’ chemical reactions, which preferably react only with the chemical reporter group. Key to the success of this approach is the availability of bio-orthogonal reactions that are fast, biocompatible, and chemoselective.
The incorporation of two chemical reporters followed by chemoselective bio-orthogonal labelling is an extension of this ‘tag and modify’ strategy, which offers the opportunity to label two different biomolecules in cellulo. Additionally, the incorporation of different chemical reporters within a single biomolecule followed by dual differential labelling is a nascent approach to probe the dynamics of a single biomolecule. At present, this is highly challenging to achieve with current bio-orthogonal strategies if discretely tagged products (i.e., without a mixture of products) are required.
Previous work – Our collaborative team has recently identified the utility of aromatic ynamines as a superior reagent for Cu-catalyzed alkyne-azide cycloaddition (CuAAC) reactions.[1-2] These alkyne surrogates require significantly less Cu catalyst are the only alkyne reagents reported to date which enable chemoselective control in a sequential two-step CuAAC process.[1,3]
Project Objective - The principal objective of this studentship is to develop aromatic ynamines into a powerful new bio-orthogonal reaction platform for the chemoselective tagging of glycoproteins in prostate cancer cells.
The specific aims of the project are to:
(i) gain a mechanistic understanding of the enhanced chemoselectivity of ynamines in CuAAC reactions, and potentially across other bio-orthogonal reaction classes.
(ii) establish conditions for chemoselective modification of biomolecules.
(iii) explore the utility of ynamines as glycoprotein tagging agents of prostate cancer cells.
Academic Environment - The student undertaking this project will receive unparalleled experience in all aspects of mechanistic organic chemistry and cancer chemical biology within our inter-disciplinary collaboration. The Burley group (www.burleylabs.co.uk, University of Strathclyde) has extensive experience in small molecule synthesis, solid phase peptide/nucleic acid synthesis and the development of bioconjugation reagents. The Watson group (University of St. Andrews from January 2018, http://www.watsonresearchgroup.co.uk
) has specialised expertise in mechanistic organic chemistry and has applied this mechanistic insight to develop improved chemical processes for a suite of C-C, C-O and C-N bond forming methods. The cell uptake and selectivity experiments will be conducted in collaboration with Prof David Elliott and his team in Northern Institute for Cancer Research (Newcastle University).
1. Hatit, M.Z.C.; Sadler, J.C.; McLean, L.A.; Whitehurst, B.C.; Seath, C.P.; Humphreys, L.D.; Young, R.J.; Watson, A.J.B.; Burley, G.A. "Chemoselective Sequential Click Ligations Directed by Enhanced Reactivity of an Aromatic Ynamine" Organic Letters, 2016, 18, 1694-1697.
2. Seath, C.P.; Burley, G.A. & Watson, A.J.B. "Determining the Origin of Rate-Independent Chemoselectivity in CuAAC Reactions: An Alkyne-Specific Shift in Rate-Determining Step" Angewandte Chemie International Edition, 2017, 56, 334-3318.
3. Hatit, M.Z.C.; Seath, C.P.; Watson, J.B.; Burley, G.A. "A Strategy for Conditional Orthogonal Sequential CuAAC Reactions Using a Protected Aromatic Ynamine" Journal of Organic Chemistry, 2017, 82, 5461-5468.
4. Perrett, A.J.; Dickinson, R.L.; Krpetic, Z., Brust, M.; Lewis, H.; Eperon, I.C.; Burley, G.A. "Conjugation of PEG and gold nanoparticles to increase the accessibility and valency of tethered RNA splicing enhancers" Chemical Science, 2013, 4, 257-265.