scholarly journals Substrate specificity and distribution of UDP-GalNAc:sialylparagloboside N-acetylgalactosaminyltransferase in the human stomach

1992 ◽  
Vol 288 (1) ◽  
pp. 161-165 ◽  
Author(s):  
T Dohi ◽  
A Nishikawa ◽  
I Ishizuka ◽  
M Totani ◽  
K Yamaguchi ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Gastric Cancer Tissue ◽  
Reversed Phase ◽  
Cancer Tissue ◽  
Transferase Activity ◽  
Fundic Mucosa ◽  
Pyloric Mucosa ◽  
Good Acceptor

The detailed substrate specificity of the UDP-GalNAc:sialylparagloboside N-acetylgalactosaminyltransferase to form the Sd(a+) blood group active carbohydrate determinant GalNAc beta 1-4(NeuAc alpha 2-3)Gal was studied using a membrane fraction prepared from human gastric fundic mucosa. Various sialosylated oligosaccharides and gangliosides were examined as acceptor substrates. Oligosaccharide substrates were fluorescence-labelled with 2-aminopyridine, and the transferase activity was quantified by h.p.l.c. using a reversed-phase column. The structures of the products were determined by glycosidase degradation and proton n.m.r. 3′-Sialyl-lactose (II3NeuAcLac), 3′-sialyl-lactotetraose (IV3NeuAcLc4), and 3′-sialyl-lactoneotetraose (IV3NeuAcnLc4) were good substrates for the beta 1-4GalNAc transferase in gastric fundic mucosa, but 6′-sialyl-lactoneotetraose (IV6NeuAcnLc4) or 6′-sialyl-lactose (II6NeuAcLac) were not. Gangliosides with a terminal NeuAc alpha 2-3Gal residue such as GM3, sialylparagloboside, GM1b and GD1a were also studied. The activity of beta 1-4GalNAc transfer to sialylparagloboside was much higher than that to GM2, GM1b or GD1a in spite of them having the same terminal residue. Measurement of the activity of the beta 1-4GalNAc transferase in biopsy specimens demonstrated that the activity was localized in gastric fundic mucosa and was absent in pyloric mucosa, intestinal metaplasia and gastric cancer tissue. Thus the beta 1-4GalNAc transferase present specifically in fundic mucosa required a NeuAc alpha 2-3Gal residue connected to either type-1-chain or type-2-chain oligosaccharides. In glycolipids, the acceptor specificity was restricted to NeuAc alpha 2-3Gal beta 1-4GlcNAc because the NeuAc alpha 2-3Gal beta 1-3GalNAc structure in ganglio-series glycolipids was not a good acceptor substrate.

scholarly journals Porcine, mouse and human galactose 3-O-sulphotransferase-2 enzymes have different substrate specificities; the porcine enzyme requires basic compounds for its catalytic activity

2005 ◽  
Vol 391 (1) ◽  
pp. 77-85 ◽  
Author(s):  
Akira Seko ◽  
Jun-ichi Sumiya ◽  
Katsuko Yamashita
Keyword(s):  
Catalytic Activity ◽  
Substrate Specificity ◽  
Colonic Mucosa ◽  
Post Translational Modifications ◽  
Substrate Specificities ◽  
Colonic Mucin ◽  
Basic Compounds ◽  
Kinetics Of

Sulphation of galactose at the C-3 position is one of the major post-translational modifications of colorectal mucin. Thus we partially purified a Gal 3-O-sulphotransferase from porcine colonic mucosa (pGal3ST) and studied its enzymatic characteristics. The enzyme was purified 48500-fold by sequential chromatographies on hydroxyapatite, Con A (concanavalin A)–Sepharose, porcine colonic mucin–Sepharose, Cu2+-chelating Sepharose and AMP–agarose. Interestingly, the purified pGal3ST required submillimolar concentrations of spermine or basic lipids, such as D-sphingosine and N,N-dimethylsphingosine, for enzymatic activity. pGal3ST recognized Galβ1→3GalNAc (core 1) as an optimal substrate, and had weaker activity for Galβ1→3GlcNAc (type 1) and Galβ1→4GlcNAc (type 2). Substrate competition experiments proved that a single enzyme catalyses sulphation of all three oligosaccharides. Among the four human Gal3STs cloned to date, the substrate specificity of pGal3ST is most similar to that of human Gal3ST-2, which is also strongly expressed in colonic mucosa, although the kinetics of pGal3ST and human Gal3ST-2 were rather different. To determine whether pGal3ST is the orthologue of human Gal3ST-2, a cDNA encoding porcine Gal3ST-2 was isolated and the enzyme was expressed in COS-7 cells for analysis of substrate specificity. This revealed that porcine Gal3ST-2 has the same specificity as pGal3ST, indicating that pGal3ST is indeed the porcine equivalent of Gal3ST-2. The substrate specificity of mouse Gal3ST-2 was also different from those of human and porcine Gal3ST-2 enzymes. Mouse Gal3ST-2 preferred core 1 and type 2 glycans to type 1, and the Km values were much higher than those of human Gal3ST-2. These results suggest that porcine Gal3ST-2 requires basic compounds for catalytic activity and that human, mouse and porcine Gal3ST-2 orthologues have diverse substrate specificities.

Type 2 Diabetes Overtakes Type 1 in Hispanic Girls

2008 ◽  
Vol 38 (15) ◽  
pp. 18
Author(s):  
SHERRY BOSCHERT
Keyword(s):  
Type 2 Diabetes

Molecular analysis of FVIII gene in severe HA patients of Costa Rica

2010 ◽  
Vol 30 (S 01) ◽  
pp. S150-S152
Author(s):  
G. Jiménez-Cruz ◽  
M. Mendez ◽  
P. Chaverri ◽  
P. Alvarado ◽  
W. Schröder ◽  
...  
Keyword(s):  
Factor Viii ◽  
Coagulation Factor ◽  
Costa Rican ◽  
Factor Viii Gene ◽  
Intron 22 Inversion ◽  
Intron 1 ◽  
Polymerase Chain ◽  
Inversion Analysis

SummaryHaemophilia A (HA) is X-chromosome linked bleeding disorders caused by deficiency of the coagulation factor VIII (FVIII). It is caused by FVIII gene intron 22 inversion (Inv22) in approximately 45% and by intron 1 inversion (Inv1) in 5% of the patients. Both inversions occur as a result of intrachromosomal recombination between homologous regions, in intron 1 or 22 and their extragenic copy located telomeric to the FVIII gene. The aim of this study was to analyze the presence of these mutations in 25 HA Costa Rican families. Patients, methods: We studied 34 HA patients and 110 unrelated obligate members and possible carriers for the presence of Inv22or Inv1. Standard analyses of the factor VIII gene were used incl. Southern blot and long-range polymerase chain reaction for inversion analysis. Results: We found altered Inv22 restriction profiles in 21 patients and 37 carriers. It was found type 1 and type 2 of the inversion of Inv22. During the screening for Inv1 among the HA patient, who were Inv22 negative, we did not found this mutation. Discussion: Our data highlight the importance of the analysis of Inv22 for their association with development of inhibitors in the HA patients and we are continuous searching of Inv1 mutation. This knowledge represents a step for genetic counseling and prevention of the inhibitor development.

Polymorphisms of the Plasminogen Activator Inhibitor- 1 Gene in Type 1 and Type 2 Diabetes, and in Patients with Diabetic Retinopathy

1994 ◽  
Vol 71 (06) ◽  
pp. 731-736 ◽  
Author(s):  
M W Mansfield ◽  
M H Stickland ◽  
A M Carter ◽  
P J Grant
Keyword(s):  
Diabetic Retinopathy ◽  
Plasminogen Activator Inhibitor ◽  
Allelic Frequency ◽  
Repeat Sequence ◽  
Dinucleotide Repeat ◽  
Plasminogen Activator Inhibitor 1 ◽  
The Difference ◽  
Pai 1

SummaryTo identify whether genotype contributes to the difference in PAI-1 levels in type 1 and type 2 diabetic subjects and whether genotype relates to the development of retinopathy, a Hind III restriction fragment length polymorphism and two dinucleotide repeat polymorphisms were studied. In 519 Caucasian diabetic subjects (192 type 1, 327 type 2) and 123 Caucasian control subjects there were no differences in the frequency of the Hind III restriction alleles (type 1 vs type 2 vs control: allele 1 0.397 vs 0.420 vs 0.448; allele 2 0.603 vs 0.580 vs 0.552) nor in the allelic frequency at either dinucleotide repeat sequence. In 86 subjects with no retinopathy at 15 years or more from diagnosis of diabetes and 190 subjects with diabetic retinopathy there was no difference in the frequency of Hind III restriction alleles (retinopathy present vs retinopathy absent: allele 1 0.400 vs 0.467; allele 2 0.600 vs 0.533) nor in the allelic frequencies at either dinucleotide repeat sequence. The results indicate that there is no or minimal influence of the PAI-1 gene on either PAI-1 levels or the development of diabetic retinopathy in patients with diabetes mellitus.

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