Recombinant Secale cereale Photosystem II D2 protein (psbD)
Description
Molecular and Functional Overview
The D2 protein (encoded by the psbD gene) is a transmembrane component of PSII. It partners with the D1 protein to form the reaction center heterodimer, which binds redox-active cofactors essential for electron transport . Key features include:
Expression and Purification
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Expression System: Most commonly produced in E. coli with N-terminal His tags for purification .
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Sequence: Full-length (residues 1–353) with the amino acid sequence:
MTIALGRIPKEENDLFDTMDDWLRRDRFVFVGWSGLLLFPCAYFALGGWFTGTTFVTSWY...GNAL. -
Yield: ≥90% purity via SDS-PAGE, with lyophilized or liquid formulations .
Functional Studies
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Electron Transport: The D2 protein binds plastoquinone (Q<sub>A</sub>), enabling electron transfer to Q<sub>B</sub> . Mutations in psbD disrupt PSII assembly and quinone binding .
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In Vitro Reconstitution: Truncated D2 polypeptides (e.g., 30 kDa, 25 kDa) generated via internal translation initiation retain partial function in quinone binding .
Biogenesis Insights
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Assembly Intermediates: Psb28 binding induces conformational changes in PSII, altering the Q<sub>B</sub> pocket and replacing bicarbonate with glutamate at the non-heme iron site .
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Limitations: In vascular plants, psbD transcript abundance—not translation efficiency—determines D2 synthesis rates .
Challenges and Future Directions
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Stability Issues: Repeated freeze-thaw cycles degrade the protein; aliquoting in glycerol-containing buffers is recommended .
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Functional Aggregates: Homomeric aggregates (e.g., 46 kDa) observed during in vitro translation complicate activity assays .
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Biotechnological Potential: Engineered psbD variants could enhance PSII efficiency in synthetic photosynthesis systems .
Product Specs
Note: We will prioritize shipping the format that we have in stock. However, if you have a specific format requirement, please indicate it when placing your order, and we will fulfill your request.
Note: All of our proteins are shipped with standard blue ice packs by default. If you require dry ice shipping, please inform us in advance, and additional fees will apply.
Generally, the shelf life of liquid form is 6 months at -20°C/-80°C. The shelf life of lyophilized form is 12 months at -20°C/-80°C.
