Kilgour, Samantha L. (2017) Novel tools for the capture of intermediates of iterative polyketide catalysis. PhD thesis, University of Warwick.

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Abstract

Polyketide natural products are a major source of pharmaceutical and agricultural compounds. Their biosynthesis is highly complex and the elucidation of intermediate steps is highly desirable to the scientific community for microorganism engineering purposes.

In this work, novel photoactivatable ‘chain termination’ probes were prepared as tools for the off-loading and capture of biosynthetic intermediates from polyketide synthases (PKSs); novel methods to analyse polyketide biosynthetic intermediates via FTICR-MS were also investigated.

The chemical probes herein reported are nonhydrolysable analogues of ACP-bound malonate used in polyketide biosynthesis for carbon chain elongation. This research focused on the preparation of a chemoenzymatically modified acyl carrier protein that, upon activation via UV irradiation, should compete with discrete ‘natural’ acyl carrier proteins to capture biosynthetic intermediates from challenging type II polyketide iterative assemblies. Promising preliminary results for the use of this tool in vitro were obtained in the form of putative actinorhodin ACP-bound intermediates observed and characterised by FTICR-MS. Moreover, a 4,5-dimethoxy-2-nitrobenzyl group was also prepared and successfully employed for trapping biosynthetic intermediates from the in vivo assembly of the antibiotic lasalocid A.

Lastly, mass spectrometric methods involving alkali metal adduct ions were explored in order to improve the characterisation of free and enzyme-bound biosynthetic intermediates. Overall this work contributes further to our current and future understanding of polyketide synthases and related systems.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Polyketides -- Synthesis, Natural products -- Synthesis, Intermediates (Chemistry), Carrier proteins
Official Date:	October 2017
Dates:	Date Event October 2017 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Tosin, Manuela ; O'Connor, Peter B.
Format of File:	pdf
Extent:	xxxiii, 292 pages : illustrations, charts
Language:	eng

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