Structure of the N- and O-glycans of the A-chain of human plasma .alpha.2HS-glycoprotein as deduced from the chemical compositions of the derivatives prepared by stepwise degradation with exoglycosidases

Abstract

The structure of the glycans of the A-chain of human plasma alpha 2HS-glycoprotein was established from the chemical compositions of its derivatives prepared by sequential enzymatic degradation of the carbohydrate moiety, from the determination of the kind and amount of the monosaccharides liberated after each step of the enzymatic digestion, and from the distinct specificity of the highly purified exoglycosidases. The exoglycosidases were three sialidases (Vibrio cholerae, fowl plague virus, and Arthrobacter ureafaciens), two beta-galactosidases (Streptococcus pneumoniae and bovine testis), one alpha-N-acetylgalactosaminidase, one beta-N-acetylglucosaminidase, and one alpha-mannosidase. Utilizing sialidases with different cleavage specificities, the number of alpha 2-3- and alpha 2-6-linked sialic acid residues could be separately determined. As to the beta-galactosidases, the enzyme isolated from S. pneumoniae cleaves only beta 1-4-linked galactose residues, whereas the bovine testes enzyme acts on both the beta 1-4- and beta 1-3-linked galactose residues. Jack bean beta-N-acetylglucosaminidase cleaves beta 1-2, beta 1-4, and beta 1-6 GlcNAc with higher activity for the beta 1-2. Jack bean alpha-mannosidase cleaves alpha 1-2, alpha 1-6, and alpha 1-3 Man with greater activity for alpha 1-2 and alpha 1-6. Bovine liver alpha-N-acetylgalactosaminidase cleaves O-linked GalNAc. On the basis of these results, the A-chain of alpha 2 HS-glycoprotein was found to possess two biantennary N-glycans and two O-linked trisaccharides.

Thomsen-Friedenreich-related carbohydrate antigens in normal adult human tissues: a systematic and comparative study

“…Jacalin binds to Galβ1-3GalNAcα-and its NeuAcα2,3-linked and/or NeuAcα2,6-linked forms (Swamy et al 1991;Maemura and Fukuda 1992). Pretreatment with neuraminidase from V. cholerae removes both 2,3-and 2,6-bound sialic acid residues (Watzlawick et al 1992). Therefore, we hypothesize that the different staining patterns observed may reflect the occurrence of both subtypes of s-TF [NeuAcα2-3Galβ1-3GalNAcα1-R and Galβ1-3(NeuAcα2-6)GalNAcα1-R] and their respective sialyltransferases in changing ratios in the different cells and cellular regions.…”

Prompt Chemoenzymatic Synthesis of Diverse Complex‐Type Oligosaccharides and Its Application to the Solid‐Phase Synthesis of a Glycopeptide with Asn‐Linked Sialyl‐undeca‐ and Asialo‐nonasaccharides

“…This branch specificity of Jack beans a-d-mannosidase digestion is reversed compared with Asn-penta-oligosaccharide 37. [12] Brossmer reported that the 1!6 branched in mannoside in 37 was easier digested than the 1!3-branched mannoside. Attachment of the branched NeuAc-a-2,6-Gal-b-1,4-GlcNAc-b-1,2 sequence to the mannoside-4 may alter the substrate specificity of mannosidase digestion.…”

The Serum Protein α2-HS Glycoprotein/Fetuin Inhibits Apatite Formation in Vitro and in Mineralizing Calvaria Cells

“…Due to the cystatin domains fetuins are grouped within the cystatin superfamily of proteins (14). Fetuins are both N-and O-glycosylated (15,16) and Serphosphorylated (17). Human plasma ␣ 2 -HS is proteolytically processed (17).…”