The design and synthesis of a novel thiamine cofactor for potential biocatalysis

The design and application of enzyme mimics has received more attention due to requirement of green chemistry applications within industry and academia. One way of introducing these modifications is via a cofactor, due to their location within an enzyme’s active site. A number of crucial biochemical reactions in the cell require not only the enzymes for catalysis, but also the organic cofactors or metal ions. It is therefore advantageous to utilize this common structural relationship to model a novel enzyme – cofactor system capable of undergoing chemistry not commonly undertaken by this enzyme, and which could be beneficial to the synthetic chemist. Recent research has concentrated on the synthesis of unnatural vitamin B1 motifs containing a central 1,4 - triazole motif (figure 1) first synthesised by Leeper in 2006. Figure 1: 1,4 – disubstituted triazole ThDP Synthesis of a cofactor that could theoretically carry out alternative reaction pathways and invoke novel enzyme-substrate pathways, whilst regenerating the cofactor in situ was envisaged (figure 2). Structural analogues of this coenzyme could thus be synthesised to tailor different products, thereby promoting high yields, high stereo/regiochemical control and reduced costs for industrial application. Figure 2: Proposed novel bio catalytic pathway based on 1,4 -ThDP scaffold The multi-step synthesis of some model compounds and their testing in pyruvate decarboxylase enzyme was successfully completed. Results indicated that only smaller chains are accommodated in the active site and initial attempts to synthesis a tertiary amine tether proved difficult because of intramolecular cyclisations. However, a potential novel route to benzoxyazepines was uncovered by an acid catalysed deprotection, cyclisation, elimination step. Enantiopure synthesis was also carried out, and an initial high ee% was observed, but conditions for this require further development. Lastly, the synthesis of a new difluorophosphate isostere for the diphosphate group was developed in good yield for a potential 1,4-CuAAC of our compound for further biological evaluation in PDC enzymes.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of East Anglia

Year dc:date.issued

2016

Author dc:creator

• Tinson, Ryan

Language dc:language

en