Thioredoxin(Trx) is a protein present in all organisms, from bacterias to complex beings as humans. This page will be focused on exploring the characteristics of Trx1, a cytosolic form of Trx present in eukaryotes. Trx1 has an active site composed of 2 cysteines separated by 2 aminoacids () which catalyses the reduction of other thiol-proteins and becomes oxidized. It is reduced back by Thioredoxin Reductase(TrxR), which, in the end, is reduced by NADPH. Together, the two proteins and NADPH form the system Trx[3].
To reduce other proteins, first happens an attack from Cys32, creating an intermolecular dissulfide bond, represented between residue Cys32 from Trx1 and residue Cys206 from MsrA. After it, residue Cys35 attacks Cys32, creating a dissulfide bond between the two cysteines in Trx1's catalytic site. This is the .
Although Trx1 from a great amount of organisms has only the catalytic site cysteines, the human form of Trx1 also has other , Cys 62, Cys 69 and Cys 73, which can act as regulators of the protein. enhances its antiapoptotic function in some cases, although its not necessary for it.[4]
S-nitrosation of Trx on Cys69 enhances its antiapoptotic function in some cases, although its not necessary for it.
[5]
Trx and TrxR were first discovered in 1964 in a study realized in bacteria, and were described as necessary proteins to reduce Ribonucleotide Reductase(RNR), a protein that produces deoxyribonucleotides from ribonucleotides[6]. Since 1964, functions of Trx1 different than participating in cell division were discovered, as denitrosation, transnitrosation, deglutathionylation,
One of the most important proteins that Trx reduces is Peroxiredoxin(Prx), which catalyses the reduction of Hidrogen Peroxide(H2O2) to water.
Cytosolic, nuclear, mithocondrial and secreted. Fazer distinção antes sobre a Trx1 e a Trx2. Não sei se a Trx2 também possui sítio ativo nesse lugar.
Structure
One 4 strands beta sheet involved by 5 alpha-helix. Primary structure depends on the organism. Yeast Trx (yTrx) has only 2 cysteines, the ones in the active site. Human Trx, on the other hand has 5 cysteines: Cys32, Cys35, which composes the active site, Cys62, Cys69, structural cysteines, and Cys73, an important sensor against oxidative conditions.
Function
Falar da RNR, Prx e outras proteínas que eu tenho visto que ela interage.
Disease
Relevance
Structural highlights
Post-translational changes
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