Deglycosylation of alpha 1-proteinase inhibitor by endo-beta-N-acetylglucosaminidase F.

The glycosidase endo-beta-N-acetylglucosaminidase F (endo F) from Flavobacterium meningosepticum was used for the deglycosylation of rat alpha 1-proteinase inhibitor (alpha 1 PI). alpha 1 PI containing three oligosaccharide side chains of the complex type was isolated from rat serum or from the medium of rat hepatocyte primary cultures. High-mannose-type alpha 1 PI or hybrid-type alpha 1 PI was isolated from the media of hepatocytes treated with 1-deoxymannojirimycin or swainsonine, respectively. The susceptibility of complex-type alpha 1 PI to endo F was studied in the presence of various detergents. 3-[(3-Cholamidopropyl)dimethylammonio]-1-propanesulfonate and octyl glucopyranoside turned out to be most effective. In the absence of detergents, digestion of alpha 1 PI with high concentrations of endo F and/or long times of incubation led to the formation of alpha 1 PI with one and two oligosaccharide side chains. In the presence of 0.5% octyl glucopyranoside, the major cleavage products were unglycosylated alpha 1 PI and alpha 1 PI carrying one carbohydrate side chain. In contrast to the complex-type alpha 1 PI, the high-mannose type can be totally deglycosylated by endo F even in the absence of detergents. The susceptibility of the hybrid-type alpha 1 PI to endo F is between that of the complex and the high-mannose types.