Recombinant Geobacter sp. NADH-quinone oxidoreductase subunit K 2 (nuoK2)

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Cat. No.
BT2044150
Source
in vitro E.coli expression system
Synonyms
nuoK2; GM21_4000; NADH-quinone oxidoreductase subunit K 2; NADH dehydrogenase I subunit K 2; NDH-1 subunit K 2
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Description

Definition and Biological Role

NADH-quinone oxidoreductase (NDH-1) is a membrane-bound enzyme complex involved in the electron transport chain, catalyzing electron transfer from NADH to quinones. Subunit K 2 (nuoK2) is a conserved component of NDH-1 in Geobacter species, contributing to structural stability and electron transfer efficiency . Recombinant variants of this subunit are produced to study its biochemical properties and applications in bioenergy and environmental remediation .

Biochemical Properties

PropertyDetails
EC Number1.6.99.5
Gene NamenuoK2
Protein Length100–114 amino acids (varies by species)
Molecular Weight~12–13 kDa (calculated)
TagHis-tag (common for purification)
Storage Conditions-20°C to -80°C in Tris-based buffer with 50% glycerol

Sequence Features

  • Contains transmembrane helices and conserved motifs for quinone binding .

  • Key residues involved in NADH oxidation and proton translocation .

Production and Purification

Recombinant nuoK2 is typically expressed in E. coli systems fused with affinity tags (e.g., His-tag) for purification . Key steps include:

  1. Cloning: nuoK2 gene inserted into plasmids under strong promoters (e.g., T7).

  2. Expression: Induced with IPTG in E. coli BL21 strains .

  3. Purification: Nickel-affinity chromatography due to His-tag fusion .

  4. Quality Control: >85% purity verified via SDS-PAGE .

Functional Insights

  • Electron Transfer: nuoK2 participates in coupling NADH oxidation to quinone reduction, critical for proton motive force generation .

  • Species-Specific Variations:

    SpeciesUniprot IDExpression RegionNotes
    Geobacter sulfurreducensQ746T61–102 aaFull-length, used in ELISA studies
    Geobacter bemidjiensisB5EFF3Partial sequenceMammalian cell expression system
    Geobacter sp. (strain M21)C6E8M51–100 aaThermostable variant

  • Stability: Repeated freeze-thaw cycles degrade activity; working aliquots stored at 4°C for ≤1 week .

Applications

  • Bioenergy: Enhances electron flux in microbial fuel cells due to Geobacter’s extracellular electron transfer capabilities .

  • Bioremediation: Potential use in redox-driven degradation of pollutants (e.g., uranium) .

Challenges and Future Directions

  • Structural Data: No crystal structures available; homology modeling relies on bacterial NDH-1 complexes .

  • Functional Redundancy: Multiple NDH isoforms in Geobacter complicate targeted studies .

  • Optimization: Improving thermostability and yield in heterologous systems .

Product Specs

Form
Lyophilized powder
Note: While we prioritize shipping the format currently in stock, we are happy to accommodate specific format requirements. Please indicate your preference in the order notes, and we will fulfill your request if possible.
Lead Time
Delivery times may vary depending on the purchase method and location. For specific delivery time estimates, please consult your local distributors.
Note: Our proteins are standardly shipped with blue ice packs. If dry ice shipping is required, please contact us in advance, as additional charges will apply.
Notes
Repeated freezing and thawing is not recommended. For optimal stability, store working aliquots at 4°C for up to one week.
Reconstitution
Before opening, we recommend briefly centrifuging the vial to concentrate the contents at the bottom. Reconstitute the protein in sterile deionized water to a concentration of 0.1-1.0 mg/mL. For long-term storage, we suggest adding 5-50% glycerol (final concentration) and aliquotting the solution for storage at -20°C/-80°C. Our default final glycerol concentration is 50%, which can be used as a reference point.
Shelf Life
Shelf life is influenced by various factors, including storage conditions, buffer composition, temperature, and the intrinsic stability of the protein.
Generally, liquid formulations have a shelf life of 6 months at -20°C/-80°C. Lyophilized forms typically exhibit a shelf life of 12 months at -20°C/-80°C.
Storage Condition
Upon receipt, store at -20°C/-80°C. Aliquot the protein for multiple uses. Avoid repeated freeze-thaw cycles.
Tag Info
The tag type will be determined during the manufacturing process.
If you have a specific tag type requirement, please inform us, and we will prioritize developing the specified tag.
Synonyms
nuoK2; GM21_4000; NADH-quinone oxidoreductase subunit K 2; NADH dehydrogenase I subunit K 2; NDH-1 subunit K 2
Buffer Before Lyophilization
Tris/PBS-based buffer, 6% Trehalose.
Datasheet
Please contact us to get it.
Expression Region
1-100
Protein Length
full length protein
Species
Geobacter sp. (strain M21)
Target Names
nuoK2
Target Protein Sequence
MLAIENYLILSAILFAIGTIGVLTRRNAIVIFMCIELMLNAVNLTFIAFSRHLGNIDGQV FVFFVMTVAAAEAAVGLALMIAFFKNRESIDVEDVNLMKL
Uniprot No.
C6E8M5

Target Background

Function
NDH-1 facilitates electron transfer from NADH to quinones within the respiratory chain, using FMN and iron-sulfur (Fe-S) centers as intermediates. In this specific species, ubiquinone is believed to be the enzyme's immediate electron acceptor. The redox reaction is coupled to proton translocation, where four hydrogen ions are translocated across the cytoplasmic membrane for every two electrons transferred. This process conserves redox energy by generating a proton gradient.
Database Links

KEGG: gem:GM21_4000

STRING: 443144.GM21_4000

Protein Families
Complex I subunit 4L family
Subcellular Location
Cell inner membrane; Multi-pass membrane protein.

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