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BioAssay: AID 423537

Activity at human recombinant TrxR1 at pH 7.4

Methylene blue (MB) has experienced a renaissance mainly as a component of drug combinations against Plasmodium falciparum malaria. Here, we report biochemically relevant pharmacological data on MB such as rate constants for the uncatalyzed reaction of MB at pH 7.4 with cellular reductants like NAD(P)H (k = 4 M(-1) s(-1)), thioredoxins (k = 8.5 to 26 M(-1) s(-1)), dihydrolipoamide (k = 53 M(-1) more ..
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 Tested Compounds
 Tested Compounds
All(1)
 
 
Unspecified(1)
 
 
 Tested Substances
 Tested Substances
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Unspecified(1)
 
 
 Related BioAssays
 Related BioAssays
AID: 423537
Data Source: ChEMBL (574881)
BioAssay Type: Confirmatory, Concentration-Response Relationship Observed
Depositor Category: Literature, Extracted
BioAssay Version:
Deposit Date: 2010-05-26
Modify Date: 2014-08-24

Data Table ( Complete ):           View All Data
Target
Sequence: RecName: Full=Thioredoxin reductase 1, cytoplasmic; Short=TR; AltName: Full=Gene associated with retinoic and interferon-induced mortality 12 protein; Short=GRIM-12; Short=Gene associated with retinoic and IFN-induced mortality 12 protein; AltName: Full=KM-102-derived reductase-like factor; AltName: Full=Thioredoxin reductase TR1
Description ..   
Protein Family: Pyridine nucleotide-disulphide oxidoreductase, dimerization domain
Comment ..   

Gene:TXNRD1     Related Protein 3D Structures     More BioActivity Data..
Tested Compound:
Description:
Title: Interactions of methylene blue with human disulfide reductases and their orthologues from Plasmodium falciparum.

Abstract: Methylene blue (MB) has experienced a renaissance mainly as a component of drug combinations against Plasmodium falciparum malaria. Here, we report biochemically relevant pharmacological data on MB such as rate constants for the uncatalyzed reaction of MB at pH 7.4 with cellular reductants like NAD(P)H (k = 4 M(-1) s(-1)), thioredoxins (k = 8.5 to 26 M(-1) s(-1)), dihydrolipoamide (k = 53 M(-1) s(-1)), and slowly reacting glutathione. As the disulfide reductases are prominent targets of MB, optical tests for enzymes reducing MB at the expense of NAD(P)H under aerobic conditions were developed. The product leucomethylene blue (leucoMB) is auto-oxidized back to MB at pH 7 but can be stabilized by enzymes at pH 5.0, which makes this colorless compound an interesting drug candidate. MB was found to be an inhibitor and/or a redox-cycling substrate of mammalian and P. falciparum disulfide reductases, with the kcat values ranging from 0.03 s(-1) to 10 s(-1) at 25 degrees C. Kinetic spectroscopy of mutagenized glutathione reductase indicates that MB reduction is conducted by enzyme-bound reduced flavin rather than by the active-site dithiol Cys58/Cys63. The enzyme-catalyzed reduction of MB and subsequent auto-oxidation of the product leucoMB mean that MB is a redox-cycling agent which produces H2O2 at the expense of O2 and of NAD(P)H in each cycle, turning the antioxidant disulfide reductases into pro-oxidant enzymes. This explains the terms subversive substrate or turncoat inhibitor for MB. The results are discussed in cell-pathological and clinical contexts.
(PMID: 17967916)
Categorized Comment - additional comments and annotations
From BioAssay Depositor:
Assay Type: Binding
Target Type: Target is a single protein chain
Assay Data Source: Scientific Literature
Protein Target Class: enzyme reductase
Result Definitions
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TIDNameDescriptionHistogramTypeUnit
OutcomeThe BioAssay activity outcomeOutcome
1Km*Km PubChem standard valueFloatμM
2Kcat activity commentKcat activity commentString
3Kcat standard flagKcat standard flagInteger
4Kcat qualifierKcat qualifierString
5Kcat published valueKcat published valueFloat/s
6Kcat standard valueKcat standard valueFloats-1
7Km activity commentKm activity commentString
8Km standard flagKm standard flagInteger
9Km qualifierKm qualifierString
10Km published valueKm published valueFloatμM
11Km standard valueKm standard valueFloatnM

* Activity Concentration.

Data Table (Concise)
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