LIF, human, recombinant
Leukemia inhibitory factor (LIF) is a pleiotropic lymphoid factor belonging to the interleukin-6 family of cytokines. It was initially described as a factor inhibiting the proliferation of myeloid leukemia cells and inducing their differentiation into macrophages. Other activities of LIF include inhibition of adipogenesis and roles in cholinergic neuron differentiation, hematopoeisis, inflammation and bone metabolism. LIF inhibits the differentiation of embryonic stem cells, it is therefore important in ES cell culture. Human and mouse LIF share 78% amino acid homology, the human version is equally active on human and mouse cells but murine LIF is not active on human cells.
 
Lot Number 
 
01-1-88-7124
 
Available Sizes
 
10µg, 100µg, 1000µg
 
Source
 
ISOkine™ recombinant human LIF is produced in the endosperm tissue of barley grain (Hordeum vulgare).
 
Formulation
 
Sterile filtered through a 0.2 µm filter. Lyophilized from PBS, pH 7.2
 
Purity
 
Greater than 98% by SDS-PAGE gel analysis.
 
Reconstitution
 
Note: Always centrifuge the vial before opening. It is recommended to reconstitute the lyophilized protein in sterile waterto a concentration of no less than 100 µg/ml. For long term storage it is recommended to add a carrier protein (0.1% HSA or BSA).
 
Stability
 
The lyophilized protein, though stable at room temperature for few weeks, is best stored at -20°C. Reconstituted protein should be used immediay or stored in working aliquots at -20°C. Avoid repeated freeze-thaw cycles.
 
Biological Activity
 
Each batch of ISOkine™ growth factor is tested for bioactivity and verified to have comparable activity to a commercial source. The bioactivity of ISOkine™ human LIF was determined by its ability to induce proliferation of TF-1cells in a dose dependent manner. The ED50 value for this effect is typically below 0.4 ng/ml corresponding to specific activity of >2.5 x 10e6 U/mg. Optimal concentration should be determined for specific applications and cell lines.
 
Endotoxin Level
 
Endotoxin level is less than 0.005ng per µg of ISOkine™ product (< 0.05EU/µg).
 
MAT assay
 
Purified ISOkine™ product carries no pyrogenic or pro-inflammatory contaminants, as assayed with monocyte activation test using Human 10-plex Cytokine Assay measuring IL-6, TNF-alpha and IL-1beta induction. Ref. The Blood Bank, University Hospital of Iceland, Reykjavik, Iceland
 
Molecular Weight
 
Recombinant human LIF contains 180 amino acids and a 16 a.a. histidine-based tag for a total length of 196 a.a. and has a predicted molecular mass of 21.8 kDa. As a result of glycosylation, the recombinant protein migrates with an apparent molecular mass of 25-30 kDa in SDS-PAGE.

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