Sandbox Reserved 978

From Proteopedia

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Revision as of 14:12, 1 May 2015

This Sandbox is Reserved from 15-Jan-2015, through 30-May-2015 for use in the course "Biochemistry" taught by Jason Telford at the Maryville University. This reservation includes Sandbox Reserved 977 through Sandbox Reserved 986.

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Thioredoxin Reductase

Thioredoxin Reductase (TrxR) is a protein in the family of flavoproteins and whose function is very similar to proteins such as glutathione reductase. These types of proteins have two locations other than the active site for bot FAD and NADPH to bind, with the active site being the location of a oxidation/reduction reaction. This redox reaction targets the disulphide group of Thioredoxin in the active site. With the structure of TrxR varying slightly between the likes of bacteria, archaea, and other animals, the action of the family of TrxR remain the same. TrxR is utilized in the regulation of DNA translation and in apoptosis. Each member of the TrxR family has a different way to program the cell for death. These methods range from marking a protein with an extra amino acid to the reduction of H₂O₂ and even including protein repair.

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You may include any references to papers as in: the use of JSmol in Proteopedia ^[1] or to the article describing Jmol ^[2] to the rescue.

1 Function
2 Disease
3 Relevance
4 Structural highlights

Function

One function of TrxR is to reduce compounds such as H₂O₂ which This protein's mechanism is greatly related to the orientation of the FAD and NADPH domains. When the NADPH is oriented 66º off of the FAD it allows electrons to transfer from the NADPH to the FAD and through that to the active site of the enzyme and the disulphide that resides there. The disulphide is then reduced to Trx-(SH)₂ which is then used as a reducing agent for other compounds such as H₂O₂. Without the proper orientation of the two domains (FAD and NADPH) the electrons would not travel from NADPH to the FAD thus preventing the reaction completely.

A second function of this protein is utilized in the regulation of DNA translation and in apoptosis. A normal stop codon (UGA, UAA, and UAG) stops the translation of the mRNA, but in the presence of TrxR an extra Selenocysteine is added to the end of the protein chain. This extra amino acid is what marks the structure for death inside the cell. Enough of these structures in the cell and the entire cell will undergo apoptosis.

Disease

When left unregulated cell death does not perform as functioned resulting in a build-up of tissue and most often the cause of tumorous growths in the body. This includes cancerous growths as well as non-cancerous.

Relevance

There needs to be be great surveillance on TrxR. Since the enzyme's action works specifically with cell death it needs to be highly regulated. Leaving TrxR unchecked could lead to too little or too much cell death. If TrxR is mutated or inhibited apoptosis is avoided tumors can form

Structural highlights

The catalytic site for TrxR is a -Cys-Val-Asn-Val-Gly-Cys- group that is located by the FAD site allowing for the easy transport of the extra electrons from NADPH to the Thioredoxin present.

This is a sample scene created with SAT to by Group, and another to make of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes.

References

↑ Hanson, R. M., Prilusky, J., Renjian, Z., Nakane, T. and Sussman, J. L. (2013), JSmol and the Next-Generation Web-Based Representation of 3D Molecular Structure as Applied to Proteopedia. Isr. J. Chem., 53:207-216. doi:http://dx.doi.org/10.1002/ijch.201300024
↑ Herraez A. Biomolecules in the computer: Jmol to the rescue. Biochem Mol Biol Educ. 2006 Jul;34(4):255-61. doi: 10.1002/bmb.2006.494034042644. PMID:21638687 doi:10.1002/bmb.2006.494034042644

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@@ Line 18: / Line 18: @@
 == Structural highlights ==
-The catalytic site for TrxR is a -Cys-Val-Asn-Val-Gly-Cys- group that is located by the FAD site allowing for the easy transport of the extra electrons to the Thioredoxin present.
+The catalytic site for TrxR is a -Cys-Val-Asn-Val-Gly-Cys- group that is located by the FAD site allowing for the easy transport of the extra electrons from NADPH to the Thioredoxin present.
 This is a sample scene created with SAT to <scene name="/12/3456/Sample/1">color</scene> by Group, and another to make <scene name="/12/3456/Sample/2">a transparent representation</scene> of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes.

Sandbox Reserved 978

From Proteopedia

Revision as of 14:12, 1 May 2015

Thioredoxin Reductase

Contents

Function

Disease

Relevance

Structural highlights

References

Views

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