Scripps VIVO scripps research logo

  • Index
  • Log in
  • Home
  • People
  • Organizations
  • Research
  • Events
Search form
As of April 1st VIVO Scientific Profiles will no longer updated for faculty, and the link to VIVO will be removed from the library website. Faculty profile pages will continue to be updated via Interfolio. VIVO will continue being used behind the scenes to update graduate student profiles. Please contact helplib@scripps.edu if you have questions.
How to download citations from VIVO | Alternative profile options

Ability of tetrahydrobiopterin analogues to support catalysis by inducible nitric oxide synthase: Formation of a pterin radical is required for enzyme activity

Academic Article
uri icon
  • Overview
  • Identity
  • Additional Document Info
  • View All
scroll to property group menus

Overview

authors

  • Hurshman, A. R.
  • Krebs, C.
  • Edmondson, D. E.
  • Marletta, Michael

publication date

  • November 2003

journal

  • Biochemistry  Journal

abstract

  • Pterin-free inducible nitric oxide synthase (iNOS) was reconstituted with tetrahydrobiopterin (H(4)B) or tetrahydrobiopterin analogues (5-methyl-H(4)B and 4-amino-H(4)B), and the ability of bound 5-methyl-H(4)B and 4-amino-H(4)B to support catalysis by either full-length iNOS (FLiNOS) or the isolated heme domain (HDiNOS) was examined. In a single turnover with HDiNOS, 5-methyl-H(4)B forms a very stable radical, 5-methyl-H(3)B(*), that accumulates in the arginine reaction to approximately 60% of the HDiNOS concentration and decays approximately 400-fold more slowly than H(3)B(*) (0.0003 vs 0.12 s(-1)). The amount of radical (5-methyl-H(3)B(*) or H(3)B(*)) observed in the NHA reaction is very small (<3% of HDiNOS). The activity of 5-methyl-H(4)B-saturated FLiNOS and HDiNOS is similar to that when H(4)B is bound: arginine is hydroxylated to NHA, and NHA is oxidized exclusively to citrulline and (*)NO. A pterin radical was not observed with 4-amino-H(4)B- or pterin-free HDiNOS with either substrate. The catalytic activity of 4-amino-H(4)B-bound FLiNOS and HDiNOS resembles that of pterin-free iNOS: the hydroxylation of arginine is very unfavorable (<2% that of H(4)B-bound iNOS), and NHA is oxidized to a mixture of amino acid products (citrulline and cyanoornithine) and NO(-) rather than (*)NO. These results demonstrate that the bound pterin cofactor undergoes a one-electron oxidation (to form a pterin radical), which is essential to its ability to support normal NOS turnover. Although binding of H(4)B also stabilizes the NOS structure and active site, the most critical role of the pterin cofactor in NOS appears to be in electron transfer.

subject areas

  • Amino Acids
  • Arginine
  • Binding Sites
  • Biopterin
  • Catalysis
  • Dithionite
  • Electron Spin Resonance Spectroscopy
  • Enzyme Activation
  • Free Radicals
  • Freezing
  • Heme
  • Nitrates
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type II
  • Nitrites
  • Oxyhemoglobins
  • Protein Structure, Tertiary
  • Pterins
  • Recombinant Proteins
  • Time Factors
scroll to property group menus

Identity

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi035491p

PubMed ID

  • 14609340
scroll to property group menus

Additional Document Info

start page

  • 13287

end page

  • 13303

volume

  • 42

issue

  • 45

©2022 The Scripps Research Institute | Terms of Use | Powered by VIVO

  • About
  • Contact Us
  • Support