Skip to content Skip to navigation
University of Warwick
  • Study
  • |
  • Research
  • |
  • Business
  • |
  • Alumni
  • |
  • News
  • |
  • About

University of Warwick
Publications service & WRAP

Highlight your research

  • WRAP
    • Home
    • Search WRAP
    • Browse by Warwick Author
    • Browse WRAP by Year
    • Browse WRAP by Subject
    • Browse WRAP by Department
    • Browse WRAP by Funder
    • Browse Theses by Department
  • Publications Service
    • Home
    • Search Publications Service
    • Browse by Warwick Author
    • Browse Publications service by Year
    • Browse Publications service by Subject
    • Browse Publications service by Department
    • Browse Publications service by Funder
  • Help & Advice
University of Warwick

The Library

  • Login
  • Admin

Cryogenic and laser photoexcitation studies identify multiple roles for active site residues in the light-driven enzyme protochlorophyllide oxidoreductase

Tools
- Tools
+ Tools

Menon, Binuraj R. K., Waltho, Jonathan P., Scrutton, Nigel S. and Heyes, Derren J. (2009) Cryogenic and laser photoexcitation studies identify multiple roles for active site residues in the light-driven enzyme protochlorophyllide oxidoreductase. Journal of Biological Chemistry, 284 (27). pp. 18160-18166. doi:10.1074/jbc.M109.020719

Research output not available from this repository, contact author.
Official URL: http://dx.doi.org/10.1074/jbc.M109.020719

Request Changes to record.

Abstract

The light-activated enzyme NADPH-protochlorophyllide oxidoreductase (POR) catalyzes the trans addition of hydrogen across the C-17–C-18 double bond of protochlorophyllide (Pchlide), a key step in chlorophyll biosynthesis. Similar to other members of the short chain alcohol dehydrogenase/reductase family of enzymes, POR contains a conserved Tyr and Lys residue in the enzyme active site, which are implicated in a proposed reaction mechanism involving proton transfer from the Tyr hydoxyl group to Pchlide. We have analyzed a number of POR variant enzymes altered in these conserved residues using a combination of steady-state turnover, laser photoexcitation studies, and low temperature fluorescence spectroscopy. None of the mutations completely abolished catalytic activity. We demonstrate their importance to catalysis by defining multiple roles in the overall reaction pathway. Mutation of either residue impairs formation of the ground state ternary enzyme-substrate complex, pointing to a key role in substrate binding. By analyzing the most active variant (Y193F), we show that Tyr-193 participates in proton transfer to Pchlide and stabilizes the Pchlide excited state, enabling hydride transfer from NADPH to Pchilde. Thus, in addition to confirming the probable identity of the proton donor in Pchlide reduction, our work defines additional roles for these residues in facilitating hydride transfer through stabilization of the ground and excited states of the ternary enzyme complex.

Item Type: Journal Article
Divisions: Faculty of Science, Engineering and Medicine > Science > Life Sciences (2010- )
Journal or Publication Title: Journal of Biological Chemistry
Publisher: American Society for Biochemistry and Molecular Biology
ISSN: 0021-9258
Official Date: 2009
Dates:
DateEvent
2009Published
Volume: 284
Number: 27
Page Range: pp. 18160-18166
DOI: 10.1074/jbc.M109.020719
Status: Peer Reviewed
Publication Status: Published

Request changes or add full text files to a record

Repository staff actions (login required)

View Item View Item
twitter

Email us: wrap@warwick.ac.uk
Contact Details
About Us