Qkine Proteins – Handling and Storage FAQ

Storage and reconstitution

Qkine lyophilized (freeze-dried) proteins can be considerably more stable than proteins in solution during storage. This allows proteins to be shipped at room temperature – good for the environment and your experiments.

We thoroughly validate all storage and shipping of our proteins. In some cases, the intrinsic biochemical properties of the protein prevent effective lyophilization and reconstitution. In those circumstances, we store and ship proteins frozen in solution (on dry ice).

All proteins should be stored at -80 °C on receipt (or -20 °C if you don’t have access to -80 °C storage).

How to store your proteins

• Lyophilized store at -20°C or -80°C for up to 2 years
• Reconstituted store at -20 °C or -80 °C
• We recommend that single use aliquots are prepared to avoid freeze-thaw cycles

How to reconstitute lyophilized protein

1. Check the resuspension solution recommendation on the product datasheet*.
2. Centrifuge briefly before reconstituting to ensure all powder is at the bottom of the vial.
3. Add sufficient reconstitution solution to give a protein concentration of 0.05–1.0 mg/ml.
4. Allow the reconstituted sample to stand at room temperature for >1 minute before gently agitating, do not vortex and avoid foaming.
5. Prepare single-use aliquots whenever possible to avoid freeze-thaw cycles which can damage the proteins and reduce bioactivity. Store aliquots at -80 °C (or -20 °C)**.

Reconstitution solution A (Qk1001)

Solution of 10 mM HCl for use in the reconstitution of lyophilised proteins. For some proteins, physiological buffers may cause precipitation of stock solutions. Hence, Qkine recommends dissolving their lyophilized TGF beta family and other related growth factors in 10 mM HCl.

Qkine Reconstitution Solution A (Qk1001)
10 mM HCl (1:1000 dilution of concentrated HCl)

Reconstitution solution A is provided with lyophilized proteins and is free of charge.

Notes

*Physiological buffers may cause precipitation of proteins during reconstitution. This is especially important for TGF beta family and other related growth factors so it is very important that these are reconstituted in Solution A (10 mM HCl, 1:1000 dilution of concentrated HCl).

**All our proteins are supplied carrier protein-free. If compatible with your work and you are storing at lower concentrations (<50 μg/ml) adding carrier protein is highly advised (usually 1% w/v high purity BSA or equivalent – ensure all buffers are sterile-filtered).