Artificial metalloenzymes in catalysis
MetadataShow full item record
This thesis describes the synthesis, characterisation and application of artificial metalloenzymes as catalysts. The focus was on two mutants of SCP-2L (SCP-2L A100C and SCP-2L V83C) both of which possess a hydrophobic tunnel in which apolar substrates can accumulate. The crystal structure of SCP-2L A100C was determined and discussed with a special emphasis on its hydrophobic tunnel. The SCP-2L mutants were covalently modified at their unique cysteine with two different N-ligands (phenanthroline or dipicolylamine based) or three different phosphine ligands (all based on triphenylphosphine) in order to increase their binding capabilities towards metals. The metal binding capabilities of these artificial proteins towards different transition metals was determined. Phenanthroline modified SCP-2L was found to be a promising scaffold for Pd(II)-, Cu(II)-, Ni(II)- and Co(II)-enzymes while dipicolylamine-modified SCP-2L was found to be a promising scaffold for Pd(II)-enzymes. The rhodium binding capacity of two additional phosphine modified protein scaffolds was also investigated. Promising scaffolds for Rh(I)- and Ir(I)-enzymes were identified. Rh-enzymes of the phosphine modified proteins were tested in the aqueous-organic biphasic hydroformylation of linear long chain 1-alkenes and compared to the Rh/TPPTS reference system. Some Rh-enzymes were found to be several orders of magnitude more active than the model system while yielding comparable selectivities. The reason for this remarkable reactivity increase could not be fully elucidated but several potential modes of action could be excluded. Cu-, Co-, and Ni-enzymes of N-ligand modified SCP-2L A100C were tested in the asymmetric Diels-Alder reaction between cyclopentadiene and trans-azachalcone. A promising 29% ee for the exo-product was found for the phenanthroline modified protein in the presence of nickel. Further improvement of these catalyst systems by chemical means (e.g. optimisation of ligand structure) and bio-molecular tools (e.g. optimisation of protein environment) can lead to even more active and (enantio)selective catalysts in the future.
Thesis, PhD Doctor of Philosophy
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.
Showing items related by title, author, creator and subject.
Quantitative comparison of catalytic mechanisms and overall reactions in convergently evolved enzymes : implications for classification of enzyme function Almonacid, Daniel E.; Yera, Emmanuel R.; Mitchell, John B. O.; Babbitt, Patricia C. (2010-03-12) - Journal articleFunctionally analogous enzymes are those that catalyze similar reactions on similar substrates but do not share common ancestry, providing a window on the different structural strategies nature has used to evolve required ...
Nath, Neetika (University of St Andrews, 2015-06-24) - ThesisThe most widely used classification system describing enzyme-catalysed reactions is the Enzyme Commission (EC) number. Understanding enzyme function is important for both fundamental scientific and pharmaceutical reasons. ...
Large pore mesoporous silicas for application in protein adsorption, enzyme immobilisation and drug delivery Ritchie, Lyndsey K. (University of St Andrews, 2009-06-26) - ThesisA range of mesoporous materials based on SBA-15, KIT-6 and FDU-12 have been prepared using neutral block copolymers Pluronic P123 and F127 and characterised using methods including electron microscopy and nitrogen adsorption. ...