Authors:	Schmid, Ira
Title:	Bioinspired Catalytically Active Materials: ATPase Mimics and Artificial Enzymatic Cascade Reactions
Online publication date:	1-Jul-2019
Year of first publication:	2019
Language:	english
Abstract:	Most biochemical reactions in nature are catalyzed by enzymes. These biocatalysts accelerate reaction rates by lowering the activation energy and can carry out different competing and incompatible reactions at the same time. The active site of the enzyme binds to the substrate, catalyzes the reaction and releases the reactions products. The small biocatalysts are distinguished by extraordinary properties and characteristics such as high selectivity, accuracy, and exceptional high catalytic activities. These features make enzymes interesting for various applications in pharma and food industry, agriculture or waste management. However, production of natural enzymes on a large scale remains challenging. Therefore, research aims for artificial methods to mimic the properties and catalytic activities of enzymes. This thesis focusses on new approaches for the imitation of natural, single enzymes and their cooperation in enzymatic clusters. Natural, soluble enzymes frequently have a hydrophobic core and a hydrophilic shell ensuring their solubility and functionality in complex environments. Inspired by nature, the general principle of core-shell structures is used within this work. A new biopolymer conjugate with attached catalytic moieties is developed to mimic enzymatic functionality. Similar to nature’s polypeptide chains, the natural poly¬saccharide dextran is used as carrier material that allows bioorthogonal attachment of hydrophilic polymers as shielding corona as well as artificial cleavage sites. Such artificial moieties are e.g. supramolecular catalysts which can mimic enzyme like active sites. Macrocyclic polyamines are known to be highly selective in cleaving adenosine triphosphate (ATP) to its diphosphate (ADP). Cyclic polyamines with functional groups are designed to allow an attachment to the dextran-based backbone. The ATPase like enzymatic system demonstrates catalytic activity in in vitro assays and high biocompatibility. The potential application and performance of the artificial ATPase in complex cellular environment still needs to be evaluated. In addition, the cooperation of enzymes in molecular machines is mimicked. Molecular machines are multifunctional enzymatic clusters in which enzymes work together to perform complex and demanding transformations. In this thesis, a new access to such multifunctional enzymatic cascade reactions is presented using artificial methods. A catalytically active hexapeptide is conjugated to the surface of cytochrome c (Cyt c). The combination of the esterase-like activity of the histidine-containing peptide with the peroxidase activity of Cyt c results in a biomaterial that performs catalytic cascade reactions within one entity. Additionally, it is possible to transfer the designed approach to other proteins. Further experiments will focus on modifications with several functional entities to implement more complex cascade reactions. Both developed systems represent promising approaches for the mimicking of enzymes and enzymatic clusters by artificial methods. Further studies will focus on their application possibilities in vitro and enhanced multifunctionality.
DDC:	540 Chemie 540 Chemistry and allied sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 09 Chemie, Pharmazie u. Geowissensch.
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-2005
URN:	urn:nbn:de:hebis:77-diss-1000028526
Version:	Original work
Publication type:	Dissertation
License:	In Copyright
Information on rights of use:	https://rightsstatements.org/vocab/InC/1.0/
Extent:	XIII, 179 Seiten
Appears in collections:	JGU-Publikationen