Role of sugar chains in the in‐vitro activity of recombinant human interleukin 5

Abstract

The structures of O‐linked sugar chains of recombinant human interleukin 5 (rhIL‐5) produced by Chinese hamster ovary cells were determined employing high‐performance anion‐exchange column chromatography under high pH conditions. The core sequence was elucidated to be Galβ1→3‐GalNAc by its susceptibility to endo‐α‐N‐acetylgalactosaminidase and sialic acid linkages were determined using sialidase of different specificities. To investigate the role of sugar chains in the in‐vitro activity of rhIL‐5, it was digested with various glycosidases. While removal of N‐linked sugar chains resulted in 2.8‐fold increase of the activity, de‐O‐glycosylated rhIL‐5 showed 10‐fold higher activity than intact rhIL‐5, suggesting that the presence of O‐linked sugar chains suppresses the activity more effectively than that of N‐linked chains. While incubation of de‐N‐glycosylated rhIL‐5 at 70°C for 30 min decreased the activity, intact and de‐O‐glycosylated rhIL‐5 lost little activity, suggesting that N‐linked sugar chains contributed to the thermostability of the molecule. Copyright © 1993, Wiley Blackwell. All rights reserved