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Site‐directed mutagenesis reveals the importance of disulfide bridges and aromatic residues for structure and proliferative activity of human Interleukin‐4
Author(s) -
Kruse Niels,
Lehrnbecher Thomas,
Sebald Walter
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)80939-z
Subject(s) - mutagenesis , tyrosine , chemistry , site directed mutagenesis , mutant , disulfide bond , biological activity , biochemistry , in vitro , mutation , gene
Mutant proteins (muteins) of human Interleukin‐4 (IL4) were constructed by means of in vitro mutagenesis. The muteins were expressed in E. coli , submitted to a renaturation and purification protocol and analysed for biological activity. Exchange of the cysteines at either position 46 or 99 which form one of the three disulfide bridges resulted in a nearly complete loss of biological activity and an unstable protein. The exchange of tyrosine 124 also inactivated the protein, while a mutation of tyrosine 56 left some residual activity. Exchange of the other four cysteines or of the single tryptophane had smaller effects.