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

A sialidase from Bacteroides fragilis SBT3182 was purified 2,240-fold to apparent homogeneity by ammonium sulfate precipitation and sequential chromatographies on DEAE-Toyopearl 650M, Hydroxyapatite, MonoS and Superose6 columns. The N-terminal amino acid sequence of this sialidase, Ala-Asp-X-Ile-Phe-Val-Arg-Glu-Thr-Arg-Ile-Pro-, was determined. Substrate specificity of this enzyme using a variety of sialoglycoconjugates showed a 1.5- and 2.2-fold preference for sialyl alpha 2-8 linkages when compared with alpha 2-3 and alpha 2-6 bound sialic acids, respectively. The native sialidase had a molecular weight of 165kDa, as determined by Superose6 gel filtration chromatography and consisted of three subunits each of 55kDa by SDS-polyacrylamide gel electrophoresis. This enzyme had optimal activity at pH6.1 with colominic acid as substrate.
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PMID:Purification and characterization of a sialidase from Bacteroides fragilis SBT3182. 133 98

The Neu1 locus, in the S region of the murine histocompatibility-2 complex, regulates the sialic acid content of several liver lysosomal enzymes. Three alleles, Neu1a, Neu1b, and Neu1c, have been described on the basis of differential sialylation of the enzyme liver acid phosphatase. The Neu1a allele occurs in a small number of mouse strains, e.g., SM/J and is associated with sialidase deficiency. We recently described G9, a sialidase gene in the human major histocompatibility complex (Milner et al. (1997) J. Biol. Chem., 272, 4549-4558), and we now report the characterization of the equivalent gene in mouse. The protein product of the murine G9 gene is 409 amino acids in length and is 83% identical to its human orthologue. Expression of the murine G9 protein in insect cells has confirmed that it is a sialidase, with optimal activity at pH 5. To elucidate the basis of sialidase deficiency in mouse strains carrying the Neu1a allele, we have sequenced the G9 coding regions from mice carrying the three Neu1 alleles and hence defined the amino acid sequence characteristic of each allotype. Of particular interest is a Leu-209 to Ile mutation that is unique to the Neu1a allotype and is associated with reductions in sialidase activity of approximately 68% and approximately 88% compared to the Neu1b and Neu1c allotypes, respectively, when these three protein variants are expressed in insect cells. Additional factors, such as differential expression, may also influence the activities of the Neu1 allotypes in vivo. We have observed that the level of G9 mRNA is substantially reduced in mice carrying the Neu1a allele compared to the Neu1b (85-95% reduction) and Neu1c (approximately 70% reduction) alleles.
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PMID:Cloning and characterization of a sialidase from the murine histocompatibility-2 complex: low levels of mRNA and a single amino acid mutation are responsible for reduced sialidase activity in mice carrying the Neu1a allele. 936 40

Here we report the cDNA sequence of a human ganglioside sialidase. The cDNA was isolated from a human brain cDNA library by screening with a 240 bp probe generated by polymerase chain reaction using primers based on the sequences of rat cytosolic and bovine membrane sialidases which we previously cloned. The 3.0 kb cDNA encodes an open reading frame of 436 amino acids containing a putative transmenbrane domain and an Arg-Ile-Pro and three Asp-box sequences characteristic of sialidases and showing overall 83% and 39% identities to the bovine and rat enzymes, respectively. Northern blot analysis revealed high expression in skeletal muscle and testis, but low level in kidney, placenta, lung, and digestive organs. Transient expression of the cDNA in COS-1 cells resulted in a 130-fold increase in sialidase activity compared to the control level, and the activity was found to be almost specific for gangliosides. Fluorescent in situ hybridization allowed the human sialidase gene localized to chromosome 11 at q 13.5.
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PMID:Cloning, expression, and chromosomal mapping of a human ganglioside sialidase. 1040 17

In contrast to the production of virus and cell lysis seen in baby hamster kidney cells (BHK-21) infected with the strain 1086C of encephalomyocarditis virus (EMCV), in buffalo rat liver cells (BRL) neither virus replication nor cytopathic effects were observed. After 29 passages in BRL cells, each alternating with boosts of the recovered virus in BHK-21 cells, the virus acquired the ability to replicate effectively in BRL cells, attaining virus titres comparable to those in BHK-21 cells and producing complete cell destruction. The binding of virus on BRL cells was increased after adaptation and was similar to that observed on BHK-21 cells. Treatment of BRL cells with sialidase resulted in an 87 % reduction in virus binding and inhibition of infection. Sequence analyses revealed three mutations in the VP1 amino acid sequence of the adapted virus at positions 49 (Lys-->Glu), 142 (Leu-->Phe) and 180 (Ile-->Ala). The residue 49 is exposed at the surface of the capsid and is known to be part of a neutralization epitope. These results suggest that the adaptation of EMCV to BRL cells may have occurred through a mutation in a neutralizing site that confers to the virus a capacity to interact with cell surface sialic acid residues. Taken together, these data suggest a link between virus neutralization site, receptor binding and cell permissivity to infection.
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PMID:Efficient infection of buffalo rat liver-resistant cells by encephalomyocarditis virus requires binding to cell surface sialic acids. 1908 88