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Methionine sulfoxide reductases

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Date Issued:
2009 -
Summary:
The methionine sulfoxide reductase (Msr) enzymes catalyze the reduction of methionine sulfoxide (Met(O)) to methionine. The Msr enzymes protect cells against oxidative stress and may have a role in aging. The MsrA family of enzymes reduces stereospecifically the S epimer of free and protein-bound Met(O) while the MsrB family reduces the R epimer of Met(O) in proteins. It has been generally accepted, primarily from studies on MsrA, that the biological reductant for the Msr enzymes is thioredoxin (Trx), although high levels of dithiothreitol (DTT) can be used as the reductant in vitro. In contrast, certain MsrB enzymes show less than 10% of the activity with Trx as compared to DTT. This raises the possibility that in animal cells Trx may not be the direct hydrogen donor for the MsrB enzymes. Studies with bovine liver extracts have shown that thionein, the apoprotein of metallothionein, can function as a reductant for the Msr proteins. Certain selenium compounds such as selenocystamine and selenocystine can also serve as potent reducing agents for the Msr enzymes. Since an increased activity of Msr enzymes can reduce the level of oxidative damage in tissues, compounds that could activate Msr may have therapeutic potential. A high-throughput screening assay has been developed to screen large chemical libraries to find activators of MsrA, as well as specific inhibitors that could be useful research tools. This study will be done in collaboration with The Scripps Florida Research Institute. Sulindac was originally developed as a non-steroidal anti-inflammatory drug but has also shown efficacy in the treatment of certain cancers. The S epimer of sulindac is known to be reduced by MsrA, but the enzymes responsible for reduction of the R epimer are not known.
Title: Methionine sulfoxide reductases: studies on the reducing requirements and role in the metabolism of sulindac.
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Name(s): Brunell, David J.
Charles E. Schmidt College of Science
Department of Biological Sciences
Type of Resource: text
Genre: Electronic Thesis Or Dissertation
Date Issued: 2009 -
Publisher: Florida Atlantic University
Physical Form: electronic
Extent: xiv, 111 p. : ill. (some col.)
Language(s): English
Summary: The methionine sulfoxide reductase (Msr) enzymes catalyze the reduction of methionine sulfoxide (Met(O)) to methionine. The Msr enzymes protect cells against oxidative stress and may have a role in aging. The MsrA family of enzymes reduces stereospecifically the S epimer of free and protein-bound Met(O) while the MsrB family reduces the R epimer of Met(O) in proteins. It has been generally accepted, primarily from studies on MsrA, that the biological reductant for the Msr enzymes is thioredoxin (Trx), although high levels of dithiothreitol (DTT) can be used as the reductant in vitro. In contrast, certain MsrB enzymes show less than 10% of the activity with Trx as compared to DTT. This raises the possibility that in animal cells Trx may not be the direct hydrogen donor for the MsrB enzymes. Studies with bovine liver extracts have shown that thionein, the apoprotein of metallothionein, can function as a reductant for the Msr proteins. Certain selenium compounds such as selenocystamine and selenocystine can also serve as potent reducing agents for the Msr enzymes. Since an increased activity of Msr enzymes can reduce the level of oxidative damage in tissues, compounds that could activate Msr may have therapeutic potential. A high-throughput screening assay has been developed to screen large chemical libraries to find activators of MsrA, as well as specific inhibitors that could be useful research tools. This study will be done in collaboration with The Scripps Florida Research Institute. Sulindac was originally developed as a non-steroidal anti-inflammatory drug but has also shown efficacy in the treatment of certain cancers. The S epimer of sulindac is known to be reduced by MsrA, but the enzymes responsible for reduction of the R epimer are not known.
Summary: An activity has been purified from rat liver which is capable of reducing the R epimers of sulindac, free Met(O) and a dabsylated Met(O) substrate, the latter suggesting that this enzyme may have properties similar t o the MsrB enzymes. The oxidation of the epimers of sulindac to sulindac sulfone has also been characterized, and the members of the cytochrome P450 family involved in the oxidation have been identified.
Identifier: 435767559 (oclc), 227979 (digitool), FADT227979 (IID), fau:3462 (fedora)
Note(s): by David J. Brunell.
Thesis (Ph.D.)--Florida Atlantic University, 2009.
Includes bibliography.
Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.
Subject(s): Cellular signal transduction
Proteins -- Chemical modification
Biochemical markers
Oxidation-reduction reaction
Persistent Link to This Record: http://purl.flvc.org/FAU/227979
Use and Reproduction: http://rightsstatements.org/vocab/InC/1.0/
Host Institution: FAU