English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
Add to Basket
 Local TagsRelease HistoryDetailsSummary
  Directed Evolution as a Method to Create Enantioselective Cyclohexanone Monooxygenases

Brunner, B. (2004). Directed Evolution as a Method to Create Enantioselective Cyclohexanone Monooxygenases. PhD Thesis, Karl-Franzens-Universität Graz, Graz.

Item is

 

show all hide all

Basic

show hide
Item Permalink: https://hdl.handle.net/11858/00-001M-0000-000F-967B-1 Version Permalink: https://hdl.handle.net/21.11116/0000-000D-8B6E-C
Genre: Thesis

Files

show Files

Locators

show

Creators

show
hide
 Creators:
Brunner, Birgit1, Author           
Affiliations:
1Research Department Reetz, Max-Planck-Institut für Kohlenforschung, Max Planck Society, ou_1445588              

Content

show
hide
Free keywords: -
 Abstract: Directed evolution is a very useful tool for targeted improvement of enzyme properties [1-7]. In the present dissertation it was used to improve the enantioselectivity of the cyclohexanone monooxygenases (CHMO) from Acinetobacter cal. NCIMB 9871 towards two different types of substrates. The CHMO is a 61 kDa NADPH dependent monomeric flavoprotein [8, 9] and catalyzes the introduction of an oxygen atom from molecular oxygen into a substrate [10]. Due to the ambivalent character of the peroxyflavin, the CHMO can catalyze Baeyer-Villiger reactions of electron-deficient substrates, such as cyclic ketones and the oxidation of electron-rich substrates, such as sulfides.
The CHMO-wt converts 4-hydroxycyclohexanone, which was used as the model substrate, leading to an ee of 9 % in slight favor of (R)-lactone [11]. In the course of the evolutionary project mutants were created which convert the 4-hydroxycyclohexanone to the (R)-lactone with ee of 90% and to the (S)-lactone with ee of 83%.
p-Methylbenzyl methyl sulfide was used as model substrate for the second substrate type and is converted by the CHMO-wt with an ee of 5% in slight favor of (R)-p-methylbenzyl methyl sulfoxide [12]. In the course of the same evolutionary project mutants were created converting the p-methylbenzyl methyl sulfide to (R)-or the (S)-sulfoxide with an ee > 99 %.
Sequencing and saturation studies identify amino acid position 432 as significant for the enantioselective conversion of both substrates.

Details

show
hide
Language(s): eng - English
 Dates: 2004-09-232004-09-23
 Publication Status: Issued
 Pages: 144
 Publishing info: Graz : Karl-Franzens-Universität Graz
 Table of Contents: -
 Rev. Type: -
 Identifiers: eDoc: 221795
 Degree: PhD

Event

show

Legal Case

show

Project information

show

Source

show