Thioredoxin, a Singlet Oxygen Quencher and Hydroxyl Radical Scavenger: Redox Independent Functions

Thioredoxin, a Singlet Oxygen Quencher and Hydroxyl Radical Scavenger: Redox Independent Functions Thioredoxin is a ubiquitous small protein known to protect cells and tissues against oxidative stress. However, its exact antioxidant nature has not been elucidated. In this report, we present evidence that human thioredoxin is a powerful singlet oxygen quencher and hydroxyl radical scavenger. Human thioredoxin at 3 μM caused 50% inhibition of TEMP- 1 O 2 (TEMPO) adduct formation in a photolysis EPR study. In contrast, Escherichia coli thioredoxin caused 50% inhibition of TEMPO formation at 80 μM. Both E. coli thioredoxin and human thioredoxin inhibited • OH dependent DMPO-OH formation as demonstrated by EPR spectrometry. The quenching of 1 O 2 or scavenging of • OH was not dependent upon the redox state of thioredoxin. Using a human thioredoxin in which the structural cysteines were mutated to alanine, Trx-C3A, we show that structural cysteines that do not take part in the catalytic functions of the protein are also important for its reactive oxygen scavenging properties. In addition, using a quadruple mutant Trx-C4A, where one of the catalytic cysteines, C35 was mutated to alanine in addition to the mutated structural cysteines, we demonstrated that catalytic cysteines are also required for the scavenging action of thioredoxin. Identification of thioredoxin as a 1 O 2 quencher and • OH scavenger may be of significant importance in explaining various redox-related antioxidant functions of thioredoxin. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Biochemical and Biophysical Research Communications Elsevier

Thioredoxin, a Singlet Oxygen Quencher and Hydroxyl Radical Scavenger: Redox Independent Functions

Loading next page...
 
/lp/elsevier/thioredoxin-a-singlet-oxygen-quencher-and-hydroxyl-radical-scavenger-UHvpV5boHv
Publisher
Elsevier
Copyright
Copyright © 2000 Academic Press
ISSN
0006-291x
D.O.I.
10.1006/bbrc.2000.3689
Publisher site
See Article on Publisher Site

Abstract

Thioredoxin is a ubiquitous small protein known to protect cells and tissues against oxidative stress. However, its exact antioxidant nature has not been elucidated. In this report, we present evidence that human thioredoxin is a powerful singlet oxygen quencher and hydroxyl radical scavenger. Human thioredoxin at 3 μM caused 50% inhibition of TEMP- 1 O 2 (TEMPO) adduct formation in a photolysis EPR study. In contrast, Escherichia coli thioredoxin caused 50% inhibition of TEMPO formation at 80 μM. Both E. coli thioredoxin and human thioredoxin inhibited • OH dependent DMPO-OH formation as demonstrated by EPR spectrometry. The quenching of 1 O 2 or scavenging of • OH was not dependent upon the redox state of thioredoxin. Using a human thioredoxin in which the structural cysteines were mutated to alanine, Trx-C3A, we show that structural cysteines that do not take part in the catalytic functions of the protein are also important for its reactive oxygen scavenging properties. In addition, using a quadruple mutant Trx-C4A, where one of the catalytic cysteines, C35 was mutated to alanine in addition to the mutated structural cysteines, we demonstrated that catalytic cysteines are also required for the scavenging action of thioredoxin. Identification of thioredoxin as a 1 O 2 quencher and • OH scavenger may be of significant importance in explaining various redox-related antioxidant functions of thioredoxin.

Journal

Biochemical and Biophysical Research CommunicationsElsevier

Published: Oct 22, 2000

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create folders to
organize your research

Export folders, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off