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Qkine growth factors storage and handling2021-09-06T10:38:35+00:00

Qkine protein storage and handling

lyophilized proteins

storage

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.

reconstitution instructions

  • centrifuge briefly before reconstituting
  • resuspension in buffer stated on data sheet
  • for some proteins physiological buffers may cause precipitation of stock solutions, hence we recommend dissolving our lyophilized TGF beta family and other related growth factors in 10 mM HCl (1:1000 dilution of concentrated HCl), check data sheet for correct reconstitution buffer
  • reconstitute to a protein concentration of 0.05–1.0 mg/ml
  • allow the reconstituted sample to sit at room temperature for a few minutes before gently agitating
  • do not vortex, foaming must be avoided
  • for maximum protein recovery of larger sample sizes, reconstitute in approximately 80% of the total volume as above, transfer reconstituted sample to a fresh tube and rinse the original tube with the remaining solution, pool the samples
  • our proteins are supplied carrier protein-free, if compatible with your work carrier protein may be added. if you are storing at low concentrations (<50 ug/ml) carrier protein is highly advised
  • divide the solution into suitable aliquots, we recommend that single-use aliquots should be prepared to avoid freeze-thaw cycles
download reconstitution guide

reconstitution solution finder

recommended buffer:

10 mM HCl
from June 2021 we will send this buffer to you with your product to make reconstitution easy
H20
this protein is provided frozen, dilution can be performed with your choice of media or buffer

reconstitution calculator

mass in vial (ug)
desired concentration (ug/ml)

volume (ul)

FAQs

Carrier vs carrier- protein free? When would/wouldn’t I want a carrier protein?2021-02-26T20:16:51+00:00

Adding a carrier protein increases protein stability, extends shelf life, allows the protein to be stored at more dilute concentrations, and helps avoid the product sticking to the walls of the vial. Consequently, adding carrier proteins can be very helpful. However, most carrier proteins are animal-derived so for animal-free and sensitive applications and assays for which BSA might interfere with the assay, carrier-free proteins are the way to go. If compatible with your work, you can add your own carrier proteins, such as BSA, HSA or gelatin when you make aliquots. Adding your own carrier allows you to select an application-compatible carrier. We recommend always using a high-purity carrier protein.

How to store growth factors2021-02-26T20:18:15+00:00

Growth factor shelf life is influenced by many factors, including storage state, buffer ingredients, storage temperature and the stability of the protein itself. Generally speaking, growth factors are most stable when lyophilized.  Our lyophilized proteins have been verified to be stable at room temperature for 3 days, or frozen for up to 2 years (either at -20 oC or -80 oC).

Once reconstituted, recombinant proteins can be stored at 4oC for 1-2 weeks, however we recommend freezing single use aliquots and defrosting fresh each time to ensure maximum protein stability and activity. Reconstituted proteins can be stored frozen for up to 1 year. When freezing reconstituted growth factors prepare single use aliquots. Every freeze-thaw cycle may cause some denaturation of the protein so repeated freeze-thaw cycles should be avoided. Always check the product sheet for freezing recommendations, but generally -20°C is suitable for short-term storage and -80°C for long term storage.

Lyophilized proteins: what does it mean and what are the pros and cons?2021-02-26T20:20:53+00:00

Lyophilized (freeze dried) proteins are considerably more stable than proteins in solution, consequently many proteins ship in lyophilized forms. This extends the time and temperature range at which the proteins can be shipped while maintaining the activity of the protein – good for the environment and your experiments. Lyophilized proteins are generally stable at room temperature for one month (we verify stability over a standard 3-day shipping cycle), or frozen at -20 oC or -80 oC for 2 years. However, on occasion lyophilization can cause partial loss of activity and damage protein structure, so some proteins are supplied in buffer.

Stability of lyophilized proteins at room temperature2021-02-26T20:23:40+00:00

We have compared our lyophilized proteins incubated at 37 °C for 3 days with those stored at -80 °C and found no difference in their bioactivity (EC50) using our standard assays. Therefore, as part of our commitment to the environment and supporting more eco-friendly packaging, we send all of our lyophilized proteins at room temperature, avoiding the need for dry ice, ice packs and gels.

Sterility of protein stock solutions2021-02-26T20:27:14+00:00

Every effort is made to ensure samples are sterile; however, we recommend sterile filtering after dilution in media or the final working solution.

Handling guidance for lyophilized cytokines including Activins, BMPs and GDF152021-02-26T20:29:25+00:00

TGF beta family proteins and other growth factors can be very poorly soluble in physiological solutions.  Please follow the handling guidance for lyophilized cytokines below to minimize loss of protein due to precipitation or adsorption to plastic.  We advise storing the recombinant protein at very low pH before dilution in cell culture media or final working solutions. Low pH will also assist in maintaining the correct disulfide structure of the protein by minimizing disulfide bond exchange reactions.

  • Resuspension in physiological buffers may cause precipitation of stock solutions, hence we recommend dissolving our lyophilized cytokines in 10 mM HCl (1:1000 dilution of concentrated HCl) while keeping the protein concentration at 50 µg/ml or above, in order to avoid loss by adsorption to plasticware.
  • To ensure you recover all of the protein, let the sample sit for a few minutes with the solubilization buffer at room temperature and pipette gently up and down (avoid foaming).
  • Rinse the tube with some more 10 mM HCl and pool with the rest.
  • The protein is tolerant of some freeze and thaw cycles, but as always with proteins, it is better to aliquot and store frozen.
  • Our proteins are supplied carrier-protein free.  If compatible with your work, add carrier protein of your choice such as BSA, HSA or gelatin to further minimize loss by adsorption.
  • Store in -80°C for long term storage. -20°C for short-term.

Every effort is made to ensure samples are sterile; however, we recommend sterile filtering after dilution in media or the final working solution.

frozen proteins

storage

Store at -20°C or -80°C. We recommend that single use aliquots are prepared to avoid freeze-thaw cycles.

handling instructions

  • thaw the sample on ice, spin briefly and dilute with PBS to the required concentration
  • our proteins are supplied carrier protein-free, if compatible with your work carrier protein may be added. if you are storing at low concentrations (<50 ug/ml) carrier protein is highly advised
  • divide the solution into suitable aliquots, we recommend that single-use aliquots should be prepared to avoid freeze-thaw cycles
  • every effort is made to ensure samples are sterile however we recommend sterile filtering after dilution in media or the final working solution

contact us

we are here to help! Any question please get in touch using the online form or send us at email to support@qkine.com

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