Reduction of biological activity of murine recombinant interleukin‐1β by selective deamidation at asparagine‐149

Abstract
A biologically active preparation of murine recombinant interleukin‐1β (mIL‐1β) fromEscherichia coli cell lysates contained two forms of mIL‐1β with pI 8.7 and pI 8.1, respectively. Treatment with 0.1 M Tris, pH 8.5, at 37°C for 35 h converted the pI 8.7 form to the pI 8.1 form by the selective deamidation of an asparagine residue (Asn149) in the mIL‐1β molecule. Deamidated mIL‐1β had 3‐ to 5‐fold lower co‐mitogenic activity and receptor affinity than the unmodified form.