Cwem. Vanzuylen et al., SITE-SPECIFIC AND COMPLETE ENZYMATIC DEGLYCOSYLATION OF THE NATIVE HUMAN CHORIONIC-GONADOTROPIN ALPHA-SUBUNIT, European journal of biochemistry, 231(3), 1995, pp. 754-760
Numerous studies have shown that glycosylation of the alpha-subunit of
human chorionic gonadotropin (alpha hCG) is essential for the biologi
cal activity of this hormone. To obtain detailed insight into the func
tion of N-glycosylation, the availability of site-specifically and ful
ly deglycosylated alpha-subunits obtained under non-denaturing conditi
ons is a prerequisite. NMR spectroscopy in combination with FAB-mappin
g demonstrates that only Asn52 of the alpha-subunit is accessible to d
igestion by peptide-N-4-(N-acetyl-beta-glucosaminyl)asparagine amidase
F under native conditions. Treatment of native alpha hCG with endo-be
ta-N-acetylglucosaminidase B results in full deglycosylation yielding
alpha hCG with one GlcNAc residue at both Asn52 and Asn78.