MOLECULAR DESIGN OF IL-15 AND ITS MUTANTS
人白介素15及突变体的分子设计

The three dimensional (3-D) structure of IL-15 and its two mutants (4 amino acids-deleted at N-terminal or 3 amino acids -deleted at C-terminal) are constructed by means of computer-guided homology modeling techniques with the crystal structure of IL-2 as a template. The structures are optimized with molecular mechanism and molecular dynamics under CVFF-force field. Furthermore, the similarity and difference of the three proteins in biological activities are predicted based on the analysis of residues hydrophilic and hydrophobic characteristics and surface electrostatic potential distribution of these proteins. IL-15 and its two mutants are expressed in E.coli and their bioactivities are tested with CTLL-2 proliferation assay and LAK-induction assay. The results show that N-terminal mutant loses CTLL-2 proliferation stimulation activity but keeps the LAK-induction activity from PBMC,while C-terminal mutant increases both of the two bioactivities. These results correspond to the predictions.