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A Convenient and General Expression Platform for the Production of Secreted Proteins from Human Cells
07:09

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Published on: July 31, 2012

The additional methionine residue at the N-terminus of bacterially expressed human interleukin-2 affects the

S Endo1, Y Yamamoto, T Sugawara

  • 1Pharmaceutical Research Division, Takeda Chemical Industries, Ltd., Yodogawa-ku, Osaka 532-8686, Japan. Endo_Satoshi@takeda.co.jp

Biochemistry
|February 15, 2001
PubMed

To gain insight into the origin of the difference in isoelectric point (pI) values for wild-type human interleukin-2 (IL-2) and IL-2 with an additional methionine residue at the N-terminus (Met-IL-2), conformational properties of the two molecular forms of IL-2 were compared by utilizing 1H NMR spectroscopy. Although overall conformations were conserved in the two forms, the presence of the additional methionine residue at the N-terminus induced chemical shift changes for residues Ala1 to Lys8 as well as for Thr133, which is located at the C-terminus. These observations indicate that the effect of the additional methionine residue is confined to the N- and C-terminal regions and unveil the existence of an interaction between the N- and C-terminal regions. The chemical shift change observed for Thr133 can be interpreted in terms of a change in pKa of the C-terminal carboxyl group, which interacts differently with the N-terminal amino group in the two forms of IL-2. It seems to be reasonable to conclude that the difference in pI values for the two forms of IL-2 is the consequence of the different interactions between the C- and N-terminal residues.

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