Interleukin molecular mass

Interleukin-6 (IL-6) is a small polypeptide with a molecular mass of 26 kDa (see Table 2). IL-6 can be induced in various cell types, including fibroblasts, macrophages/monocytes, epithelial cells, T cells, B cells, and diverse tumor cells (L4). TNF, IL-1, and LPS can stimulate IL-6 gene expression in macrophages/monocytes and fibroblasts. In vivo studies showed that systemic administration of TNF, LPS, and IL-1 was followed by a rapid induction of circulating IL-6 (B49, J2). Also, endothelin (ET) at concentrations observed pathophysiolog-ically may trigger production of IL-6 (Ml7). 

The biological activities of several other interleukins also render them likely candidates for therapeutic application. IL-5 represents one such candidate. IL-5 is a 115 amino acid glycoprotein produced mainly by activated T lymphocytes and also by mast cells. It functions as a homodimer, exhibiting a molecular mass of 45 kDa. The individual polypeptide chains interact non-covalently and the overall dimeric structure is stabilized by two interchain disulphide linkages between cysteines 42 and 84 of each chain. Removal or alterations of the cytokine s carbohydrate side-chain does not appear to affect its biological activity. 

A threefold excess of a 10 mM soln of H2NOCH2CO-Lys(FITC)-OH (10) in H20 containing 20% MeCN was added to the oxidized interleukin-8 soln (2 mg - mL 1 in 0.1 M NaOAc buffer, pH 4.6). MeCN was added to a final concentration of 10% to ensure solubilization of the reagent, and the pH of the soln was adjusted to 4.6 with glacial AcOH. After incubation for 15 h at rt in the dark, the product was purified from reactants by RP-HPLC on a C8 column. The coupling yield was estimated at 80% from the recovery of coupled protein. The conjugate had the expected molecular mass mlz calcd, 8941.6 found, 8940.6T1.0. 

The confirmation of the complete sequence of recombinant human interleukin-2 was elucidated from a tryptic digest of 7 mnol of reduced carboxymethylated interleukin-2 by Blackstock et al. [79]. The tryptic fragments were identified by molecular mass from either single-, double-, or triple-charge ions. The mobile phase contained 0.1% trifluoroacetic acid a water-acetonitrile gradient was performed. 

Interleukin eleven (IL-II) is a thrombopoietic growth factor and has a molecular mass of approximately 19,000 Da, and is nonglycosylated. The polypeptide is 177 amino acids in length. 

G24. Gross, V., Andus, T., Castell, J., Vom Berg, D., Heinrich, P. C., and Gerok, W. O- and N-glycosylation lead to different molecular mass forms of human monocyte interleukin-6. FEBS Lett. 247, 323-326 (1989). 

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