uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Global Kinetic Mechanism of Microsomal Glutathione Transferase 1 and Insights into Dynamic Enzyme Activation
Karolinska Inst, Inst Environm Med, SE-17177 Stockholm, Sweden..
Karolinska Inst, Inst Environm Med, SE-17177 Stockholm, Sweden..
Karolinska Inst, Inst Environm Med, SE-17177 Stockholm, Sweden..
Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
Show others and affiliations
2017 (English)In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 56, no 24, 3089-3098 p.Article in journal (Refereed) Published
Abstract [en]

Microsomal glutathione transferase 1 (MGST1) has a unique ability to be activated, <= 30-fold, by modification with sulfhydryl reagents. MGST1 exhibits one-third-of-the-sites reactivity toward glutathione and hence heterogeneous binding to different active sites in the homotrimer. Limited turnover stopped-flow kinetic measurements of the activated enzyme allowed us to more accurately determine the KD for the "third" low-affinity GSH binding site (1.4 +/- 0.3 mM). The rate of thiolate formation, k(2) (0.77 +/- 0.06 s(-1)), relevant to turnover, could also be determined. By deriving the steadystate rate equation for a random sequential mechanism for MGST1, we can predict K-M, k(cat), and k(cat)/K-M values from these and previously determined pre-steady-state rate constants (all determined at 5 C). To assess whether the pre-steady-state behavior can account for the steady-state kinetic behavior, we have determined experimental values for kinetic parameters at 5 degrees C. For reactive substrates and the activated enzyme, data for the microscopic steps account for the global mechanism of MGST1. For the unactivated enzyme and more reactive electrophilic substrates, pre steady -state and steady-state data can be reconciled only if a more active subpopulation of MGST1 is assumed. We suggest that unactivated MGST1 can be partially activated in its unmodified form. The existence of an activated subpopulation (approximately 10%) could be demonstrated in limited turnover experiments. We therefore suggest that MSGT1 displays a preexisting dynamic equilibrium between high- and low-activity forms.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC , 2017. Vol. 56, no 24, 3089-3098 p.
National Category
Biochemistry and Molecular Biology
Identifiers
URN: urn:nbn:se:uu:diva-329656DOI: 10.1021/acs.biochem.7b00285ISI: 000404086000011PubMedID: 28558199OAI: oai:DiVA.org:uu-329656DiVA: diva2:1142805
Funder
Swedish Research CouncilSwedish Foundation for Strategic Research Carl Tryggers foundation
Available from: 2017-09-20 Created: 2017-09-20 Last updated: 2017-09-20Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textPubMed

Authority records BETA

Svensson, Richard

Search in DiVA

By author/editor
Svensson, Richard
By organisation
Science for Life Laboratory, SciLifeLabDepartment of Pharmacy
In the same journal
Biochemistry
Biochemistry and Molecular Biology

Search outside of DiVA

GoogleGoogle Scholar

doi
pubmed
urn-nbn

Altmetric score

doi
pubmed
urn-nbn
Total: 34 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf