Midkine (MK) is a 15 kDa heparin-binding molecule originally cloned during a search for genes preferentially transcribed during retinoic acid (RA)-induced differentiation. Midkine belongs to a family of neurotrophic and developmentally-regulated heparin-binding molecules consisting of midkine, pleiotrophin (PTN/HBNF/OSF-1/HNGF-8) and the avian midkine homolog, RI-HB (for retinoic acid-inducible heparin-binding protein). Midkine is a highly basic, nonglycosylated polypeptide that contains five intrachain disulfide bonds. The predicted molecular weight is approximately 13.3 kDa, based on a mature peptide length of 118 amino acid residues in the mouse and 121 amino acid residues in the human. Across species, MK shows 87% identity between the human and murine proteins. Between family members, human MK is approximately 50% identical to human PTN, with conservation of all 10 cysteines. Initial structure-function studies indicate that the C-terminal half of MK contains the principal heparin-binding site plus the molecule’s antigenicity and neurite-promoting sequences; while both the C- and N-termini are necessary for the molecule’s neurotrophic effects. Product Properties Synonyms ARAP, Midgestation and Kidney Protein, Neurite Outgrowth-promoting Factor 2, Neurite Outgrowth-promoting Protein Accession P21741 GeneID 4192 Source E.coli-derived Human Midkine, Val21-Asp143. Molecular Weight Approximately 13.4 kDa. AA Sequence VAKKKDKVKK GGPGSECAEW AWGPCTPSSK DCGVGFREGT CGAQTQRIRC RVPCNWKKEF GADCKYKFEN WGACDGGTGT KVRQGTLKKA RYNAQCQETI RVTKPCTPKT KAKAKAKKGK GKD Tag None Physical Appearance Sterile Filtered White lyophilized (freeze-dried) powder. Purity > 97 % by SDS-PAGE and HPLC analyses. Biological Activity The biological activity determined by a chemotaxis bioassay using human neutrophils is in a concentration range of 0.1-10 ng/mL. Fully biologically active when compared to standard. Endotoxin < 1.0 EU per 1μg of the protein by the LAL method. Formulation Lyophilized from a 0.2 μm filtered concentrated solution in PBS, pH7.4. Reconstitution We recommend that this vial be briefly centrifuged prior to opening to bring the contents to the bottom. Reconstitute in sterile distilled water or aqueous buffer containing 0.1% BSA to a concentration of 0.1-1.0 mg/mL. Stock solutions should be apportioned into working aliquots and stored at ≤ -20℃. Further dilutions should be made in appropriate buffered solutions. Shipping and Storage The products are shipped with ice pack and can be stored at -20℃ to -80℃ for 1 year. Recommend to aliquot the protein into smaller quantities when first used and avoid repeated freeze-thaw cycles. Cautions 1. Avoid repeated freeze-thaw cycles. 2. For your safety and health, please wear lab coats and disposable gloves for operation. 3. For research use only!
