Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.53 (sialidase)
 2,694 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A sialidase, acting on gangliosides and mucus glycoproteins (pH optimum 4.0-4.5) was solubilized by 1% Triton X-100 and short ultrasonication from a crude mitochondrial-lysosomal fraction isolated from human liver. The enzyme was enriched over 1000-fold with the aid of affinity chromatography on equine submandibular gland mucin bound to Sepharose and 20mM Tris/HCl buffer, pH 7.5, as eluent. The sialidase exhibited a molecular mass of about 200 000 Da on Sephadex G-200. On analytical gel electrophoresis, an enzymically active protein band of about 70 000 Da was observed. A sialidase acting on sialyllactose remained in the membrane fraction and could not be solubilized.
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PMID:Solubilization and affinity chromatography of a sialidase from human liver. 714 14

Prior development of a unique androgen-receptor (AR)-negative cell line (HH870) from organ-confined (T2b) human prostate cancer (CaP) enabled comparison of the gangliosides associated with normal and neoplastic prostate epithelial cells, organ-confined versus metastatic (DU 145, PC-3), and AR-negative versus AR-positive CaP cell lines. Resorcinol-HCl and specific monoclonal antibodies were used to characterize gangliosides on 2D-chromatograms, and to visualize them on the cell surface with confocal-fluorescence microscopy. AR-negative cells expressed GM1b, GM2, GD2, GD1a, and GM3. GM1a, GD1b, and GT1b were undetectable. GM1b and GD1a were more prominent in AR-negative than in AR-positive cells. PC-3 and HH870 cells were unique in the expression of O-acetylGD2 (O-AcGD2) and two alpha2,3-sialidase-resistant, alkali-susceptible GMR17-reactive gangliosides. Expression of GD1a, GM1b, doublets of GD3, GD2, and O-AcGD2, and the presence of an additional alkali-labile-14.G2a-reactive ganglioside, two alkali-susceptible, and three alkali-resistant GMR17-reactive gangliosides makes HH870 a potential component of a polyvalent-vaccine for active-specific immunotherapy of CaP.
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PMID:Gangliosides of organ-confined versus metastatic androgen-receptor-negative prostate cancer. 1546 96

The nonpathogenic strain Arthrobacter nicotianae produces two sialidase isoenzymes, NA1 and NA2, with molecular masses of 65 kDa and 54 kDa, respectively, as determined by 10% SDS-polyacrylamide gel electrophoresis. NA1 and NA2 exhibit maximum activities at pH 4 and 5, and both show clear thermal optima at 40 degrees C. They are stable at temperatures up to 50 degrees C. The critical temperatures (T (c) = 50 degrees C and 51 degrees C) for the two isoenzymes were determined by fluorescence spectroscopy and correlate well with the temperatures of melting (T (m) = 49 degrees C and 48 degrees C), determined by CD spectroscopy. The isoenzymes are less stable against denaturation with Gdn.HCl, and the free energy of stabilization in water was calculated to be 7.6 and 8.0 kJ mol(-1), respectively. The specific activity (K (m) value) toward glucomacropeptide as a substrate was calculated to be 0.126 mM for NA1 and 0.083 mM for NA2.
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PMID:Purification and characterization of a novel sialidase from a strain of Arthrobacter nicotianae. 1580 38

Four-transmembrane-domain proteins of the tetraspanin superfamily are the organizers of specific microdomains at the membrane [TERMs (tetraspanin-enriched microdomains)] that incorporate various transmembrane receptors and modulate their activities. The structural aspects of the organization of TERM are poorly understood. In the present study, we investigated the role of gangliosides in the assembly and stability of TERM. We demonstrated that inhibition of the glycosphingolipid biosynthetic pathway with specific inhibitors of glucosylceramide synthase [NB-DGJ (N-butyldeoxygalactonojirimycin) and PPMP (D-threo-1-phenyl-2-hexadecanoylamino-3-morpholino-1-propanol.HCl)] resulted in specific weakening of the interactions involving tetraspanin CD82. Furthermore, ectopic expression of the plasma-membrane-bound sialidase Neu3 in mammary epithelial cells also affected stability of the complexes containing CD82: its association with tetraspanin CD151 was decreased, but the association with EGFR [EGF (epidermal growth factor) receptor] was enhanced. The destabilization of the CD82-containing complexes upon ganglioside depletion correlated with the re-distribution of the proteins within plasma membrane. Importantly, depletion of gangliosides affected EGF-induced signalling only in the presence of CD82. Taken together, our results provide strong evidence that gangliosides play an important role in supporting the integrity of CD82-enriched microdomains. Furthermore, these results demonstrate that the association between different tetraspanins in TERM is controlled by distinct mechanisms and identify Neu3 as a first physiological regulator of the integrity of these microdomains.
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PMID:Gangliosides play an important role in the organization of CD82-enriched microdomains. 1685 90