重组核心链霉亲和素

Due to the inclusion of stabilizers and other excipients during the lyophilization process, we recommend first using an internal assay method to accurately quantify the protein content in the product before proceeding with subsequent experiments, and adjusting the dosage as needed based on actual conditions. We suggest prioritizing the UV absorption method for quantification, as follows:

After removing the sample from low-temperature storage, allow it to equilibrate to room temperature and wipe off any condensation on the outside of the vial. Carefully open the cap to prevent loss of lyophilized powder due to splashing. Reconstitute with deionized water or buffer, ensure complete dissolution, then dilute to an appropriate concentration. Gently transfer the solution into a cuvette, using deionized water or buffer as the blank control, and measure the absorbance at 280 nm (absorbance is recommended to be maintained within the range of 0.1–1.5). Substitute this value into the following formula to calculate the protein concentration:

C = N × A₂₈₀nm / E(0.1% at 280 nm)

In the formula: C: protein mass concentration of the sample stock solution (mg/mL)

A280nm: absorbance of the protein solution measured at 280 nm

N: dilution factor

E(0.1% at 280nm): extinction coefficient of a 1 mg/mL protein solution

For example, after fully dissolving and mixing the lyophilized powder of this product, take an appropriate amount of the stock solution, dilute it 10-fold, and measure its absorbance at 280 nm to be 0.933; then the protein concentration of the stock solution is 10 × 0.933 / 3.11 = 3 mg/mL.

Precautions:

1. The recombinant core streptavidin lyophilized powder is easily soluble in water, with a solubility reaching 10 mg/mL or higher;

2. It is recommended to use purified water for dissolution;

3. If there are undissolved substances, it is recommended to extend the reconstitution time. Alternatively, insoluble particles can be removed by centrifugation or other methods before use in subsequent experiments, which will not significantly affect the total protein concentration.

4. Given the unique properties of proteins, it is advisable to prepare lyophilized powder immediately before use. After dissolution, repeated freeze-thaw cycles should be avoided. If multiple uses are required, it is recommended to aliquot and store at ≤-20℃ (preferably for no more than one year); avoid long-term storage at 4℃ (for ≤7 days).