Role of the Carbohydrate Moiety of a Glucoamylase fromAspergillus awamorivar.kawachiin the Digestion of Raw Starch

1995 ◽  
Vol 59 (1) ◽  
pp. 16-20 ◽  
Author(s):  
Masatoshi Goto ◽  
Eiji Kuwano ◽  
Werasit Kanlayakrit ◽  
Shinsaku Hayashida
Keyword(s):  
Carbohydrate Moiety ◽  
Raw Starch

scholarly journals Site-directed mutagenesis of class I HLA genes. Role of glycosylation in surface expression and functional recognition.

1987 ◽  
Vol 166 (5) ◽  
pp. 1329-1350 ◽  
Author(s):  
J A Barbosa ◽  
J Santos-Aguado ◽  
S J Mentzer ◽  
J L Strominger ◽  
S J Burakoff ◽  
...  
Keyword(s):  
Amino Acid ◽  
Gene Transfer ◽  
Aspartic Acid ◽  
Human Cell ◽  
Surface Expression ◽  
Carbohydrate Moiety ◽  
Class I ◽  
Directed Mutagenesis ◽  
L Cells

We have investigated the role of the carbohydrate moiety on the HLA-B7 molecule in mAb and CTL recognition using oligonucleotide-directed mutagenesis and gene transfer techniques. A conservative substitution of asparagine to glutamine at amino acid 86 in HLA-B7 was created to abolish the unique glycosylation site present on all HLA molecules. A second mutant B7 molecule was made by substituting asparagine-aspartic acid-threonine for the resident lysine-aspartic acid/lysine tripeptide at amino acids 176-178, thus creating an N-linked glycan at amino acid 176, which is additionally present on all known murine H-2 class I antigens. Upon gene transfer into mouse and human cell recipients, the HLA-B7M176+ mutant and normal HLA-B7 expressed identical levels of surface protein. However, the binding of two mAbs (MB40.2 and MB40.3) thought to recognize different epitopes of the HLA-B7 molecule was completely eliminated. In contrast, the HLA-B7M86- mutant displayed no surface expression (mouse L cells) or minimal surface expression (human RD cells or mouse L cells coexpressing human beta 2 microglobulin [beta 2m]) after indirect immunofluorescence (IIF) and flow cytometric analysis with a panel of 12 HLA-B7 mAb reactive with monomorphic and polymorphic determinants. Immunoprecipitation analysis demonstrated that intracellular denatured mutant protein was present. Tunicamycin treatment did not rescue the expression of HLA-B7M86- antigens to the cell surface; while interferon did induce higher levels of surface expression. Tunicamycin treatment also did not allow binding of the mAbs MB40.2 or MB40.3 to HLA-B7M176+ mutant antigens, suggesting that the carbohydrate moiety itself was not directly involved in the recognition or conformation of these mAb epitopes. Further mutation of the B7M86- molecule to create a glycan moiety at amino acid position 176 (B7M86-/176+) did not rescue normal levels of surface expression. Finally, neither mutation was seen to affect recognition by a panel of 12 allospecific CTL clones. The low expression of HLA-B7M86- on the surface of human cell transfectants was sufficient to achieve lysis, albeit at a reduced efficiency, and lysis could be increased by interferon induction of higher levels of expression. Thus, the carbohydrate moiety on HLA antigens plays a minimal or nonexistent role in recognition by available mAb and allospecific CTL clones.

Heterogeneity of horse transferrin: the role of carbohydrate moiety

2009 ◽  
Vol 15 (2) ◽  
pp. 89-101 ◽  
Author(s):  
A. Stratil ◽  
V. Tomášek ◽  
P. Bobák ◽  
V. Glasnák
Keyword(s):  
Carbohydrate Moiety

The carbohydrate portions of milk glycoproteins

1979 ◽  
Vol 46 (2) ◽  
pp. 187-191 ◽  
Author(s):  
Pierre Jollès
Keyword(s):  
Sialic Acid ◽  
Secondary Structure ◽  
Milk Protein ◽  
Neuraminic Acid ◽  
Bovine Colostrum ◽  
Carbohydrate Moiety ◽  
Cow’S Milk ◽  
Threonine Residue ◽  
Cow's Milk

SUMMARYk-Casein is the main glycoprotein of cow's milk. Its polysaccharide part is O-glycosidically linked to threonine residue 133. It contains only 3 different sugars (Gal, GalNAc, NeuNAc), but a microheterogeneity has been detected at the sugar level. Two main polysaccharides have so far been characterized. The structure of the trisaccharide is NeuNAc α → 3 Gal β1 →3 GalNAc; the tetrasaccharide contains one additional sialic acid. The polysaccharide part of ovine k-casein resembles that of bovine k-casein, but contains also N-glycolyl neuraminic acid. Human k-casein contains 3 times more carbohydrate than bovine k-casein with 2 additional sugars, GlcNAc and Fuc. The various polysaccharide parts isolated from bovine colostrum k-caseinoglycopeptide are much more complex than those obtained from the normal glycopeptide, indicating an evolution of the sugar part as a function of time after parturition. Some aspects of the secondary structure of k-casein and the role of the sugar part are discussed. The carbohydrate moiety of another milk protein, human lactotransferrin, is also discussed briefly. It is comprised of 2 identical glycan groups, N-glycosidically linked to the protein, and quite different from the k-casein carbohydrate moiety.

The Role of Carbohydrate Moiety of Gonadotropin Molecule in Transduction of Biological Signal

1984 ◽  
pp. 235-248 ◽  
Author(s):  
Uriel Zor ◽  
M. R. Sairam ◽  
Pnina Shentzer ◽  
Anat Azrad ◽  
Abraham Amsterdam
Keyword(s):  
Carbohydrate Moiety ◽  
Biological Signal

Role of the carbohydrate moiety of human choriogonadotropin in its thyrotropic activity

1984 ◽  
Vol 229 (1) ◽  
pp. 170-176 ◽  
Author(s):  
Sania Amr ◽  
Yasuyuki Shimohigashi ◽  
Pierre Carayon ◽  
Hao-Chia Chen ◽  
Bruce Nisula
Keyword(s):  
Carbohydrate Moiety ◽  
Human Choriogonadotropin ◽  
Thyrotropic Activity
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