Cytokines and Growth Factors

What is the stability of HumanKine proteins?

Unless specified otherwise in the product information sheet, our products are formulated to ensure the stability of lyophilized proteins at room temperature. It is advised to store lyophilized products at -20°C to -80°C. For reconstituted solutions of most products, short-term storage at 4°C is recommended. Extended storage of the protein solution should be at -20°C to -80°C. Keep in mind that each freeze/thaw cycle may lead to some protein denaturation, so it is not recommended to subject aliquots to multiple freeze/thaw cycle.

Why are some proteins reconstituted in acidic buffer?

Acid reconstitution buffer is especially important for proteins with a high isoelectric point, making the molecule hydrophobic at neutral pH. Failure to use the recommended buffer may result in incomplete dissolution of the cytokine or its potential loss on the surfaces of labware such as pipet tips, vials, and test tubes. Diluting the protein aliquots to the working concentration in the appropriate buffer for a specific application helps neutralize the small amount of acid added, ensuring the safe use of the protein with live cells.

Is it ok to replace Human Serum Albumin (HSA) with Bovine Serum Albumin (BSA) in reconstitution buffer?

Bovine serum albumin (BSA) can be used instead of Human Serum Albumin (HSA) in reconstitution buffer. We recommend to use recombinant HSA to keep the product animal component free. If your experiment will not be impacted by the presence of animal derived components, BSA containing buffer can be used for reconstitution.

Can HumanKine cytokines cross-react with mouse cells?

Except for a few cases, the majority of human cytokines exhibit activity on mouse cells. While many mouse cytokines can act on human cells, their specific activity might be lower compared to the corresponding human cytokine. Species specificity is observed in certain cytokines, such as interferons, GM-CSF, IL-3, and IL-4, which have minimal to no activity on non-homologous cells. In contrast, FGFs and neurotrophins are highly conserved, displaying robust activity on cells from various animal species.

How is HumanKine protein bioactivity calculated in international units(IU)?

International Unit (IU) values for our Humankine products are obtained by conducting multiple side-by-side comparisons with the WHO Reference Standard within our biological activity assay. This approach involves performing several comparison tests to account for potential outliers arising from variations in the assay, such as differences in the product, handling, assay protocol, and more. To learn more about international unit calculation, read our blog.

Why does my lyophilised protein vial appear to be empty?

The lyophilized product may have shifted from the vial's bottom during shipping/handling, scattering on the vial wall or cap. A firm tap on the bench or a brief spin in a centrifuge can help reposition the lyophilized product back to the vial's bottom. Certain pellets may present themselves as a minimal amount of material or a transparent film, attributed to the characteristics of the original buffer formulation. This appearance is typical for numerous proteins and is considered normal.