fulltext.study @t Gmail

Structural stability of E. coli transketolase to urea denaturation

Paper ID Volume ID Publish Year Pages File Format Full-Text
18648 42731 2007 10 PDF Available
Title
Structural stability of E. coli transketolase to urea denaturation
Abstract

We have characterised the early events on the urea denaturation pathway of E. coli transketolase, to provide insight into the mechanisms of enzyme deactivation that occur under biocatalytic conditions. Fluorescence intensity and circular dichroism (CD) have revealed three transitions in the denaturation pathway for holo-TK. The first step, at low urea concentration corresponds to the local restructuring of the thiamine diphosphate (TPP) binding-sites. Next, the dissociation of the TPP cofactors and partial loss of secondary structure produces a highly expanded form which is most consistent with a partially denatured dimeric form of the enzyme. The denaturation pathway of apo-TK is significantly less cooperative than that for holo-TK and their pathways converge only after the second transition indicating that the cofactors dissociate before the third and final transition to random coil. These results show that while the enzyme is deactivated initially by changes in structure associated with the cofactors, this event does not release the cofactor from the enzyme. The intermediate state formed is also consistent with that formed during reconstitution of holo-TK from apo-TK. Improvement of biocatalytic processes using TK over prolonged reaction times would, therefore, need to address the formation of this cofactor-associated intermediate state.

Keywords
CD, circular dichroism; DLS, dynamic light scattering; DTT, dithiothreitol; HPA, hydroxypyruvate; PP, pyrophosphate-binding domain; Pyr, pyrimidine-binding domain; SEC, size exclusion chromatography; TK, transketolase; TPP, thiamine pyrophosphate; PDC, py
First Page Preview
Structural stability of E. coli transketolase to urea denaturation
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us
Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 41, Issue 5, 1 October 2007, Pages 653–662
Authors
, , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us