The sequence of the first five N-terminal amino acids was determined and was found to be Asn-Trp-Val-Asn-Val.
The ED50 as determined by the dose-dependant stimulation of the proliferation of mouse CTLL-2 was found to be < 0.5 ng/ml, corresponding to a Specific Activity of 2MIU/mg.
The protein was lyophilized from a concentrated (1mg/ml) solution with 5mM Tris pH 8.0.
Sterile Filtered White lyophilized (freeze-dried) powder.
Protein quantitation was carried out by two independent methods
1. UV spectroscopy at 280 nm using the absorbency value of 0.55 as the extinction coefficient for a 0.1% (1mg/ml) solution. This value is calculated by the PC GENE computer analysis program of protein sequences (IntelliGenetics).
2. Analysis by RP-HPLC, using a calibrated solution of IL-15 as a Reference Standard.
Greater than 98.0% as determined by(a) Analysis by RP-HPLC.
(b) Analysis SDS-PAGE.
It is recommended to reconstitute the lyophilized Interleukin-15 in sterile 18MΩ-cm H2O not less than 100ug/ml, which can then be further diluted to other aqueous solutions.
Lyophilized Interleukin-15 although stable at room temperature for 3 weeks, should be stored desiccated below -18oC. Upon reconstitution IL15 should be stored at 4oC between 2-7 days and for future use below -18oC.
For long term storage it is recommended to add a carrier protein (0.1% HSA or BSA).
Please avoid multiple freeze-thaw cycles.
