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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
8
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pubmed:dateCreated |
1987-4-20
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pubmed:abstractText |
The soluble form of a bacteriophage-induced endo-N-acetylneuraminidase (Endo-N) specific for hydrolyzing oligo- or poly-alpha-2,8-linked sialosyl units in sources as disparate as bacterial and neural membrane glycoconjugates was purified approximately 10,000-fold and characterized. The enzyme appears homogenous by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and has a subunit Mr 105,000. This corresponds to one of the higher Mr phage proteins which comprises 7.5% (by weight) of the total phage protein. The holoenzyme is active at neutral pH and has a Mr by gel filtration of 328,000, suggesting that the active enzyme is a trimer. Endo-N requires a minimum of 5 sialyl residues (DP5, where DP represents degree of polymerization) for activity. The limit digest products from the alpha-2,8-linked polysialic acid capsule of Escherichia coli K1 are DP4 with some DP3 and DP1,2. DP2-4 do not appear to inhibit depolymerization of polysialic acid. Endo-N digestion of the polysialosyl moiety on neural cell adhesion molecules yields sialyl oligomers with DP3 and DP4. The presence of a terminal sialitol changes both the distribution of limit digestion products and the apparent minimum substrate size. Higher Mr alpha-2,8-linked sialyl polymers (approximately DP200) are better substrates (Km 50-70 microM) than sialyl oligomers of approximately DP10-20 (Km 1.2 mM). Endo-N activity is inhibited by DNA and several other poly-anions tested. An examination of the distribution of intermediate products shows that Endo-N binds and cleaves at random sites on the polysialosyl chains, in contrast to initiating cleavage at one end and depolymerizing processively. Endo-N can serve as a specific molecular probe to detect and selectively modify poly-alpha-2,8-sialosyl carbohydrate units which have been implicated in bacterial meningitis and neural cell adhesion.
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Mar
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pubmed:issn |
0021-9258
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
15
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pubmed:volume |
262
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
3553-61
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:3546309-Coliphages,
pubmed-meshheading:3546309-Enzyme Induction,
pubmed-meshheading:3546309-Escherichia coli,
pubmed-meshheading:3546309-Kinetics,
pubmed-meshheading:3546309-Neuraminidase,
pubmed-meshheading:3546309-Oligosaccharides,
pubmed-meshheading:3546309-Polysaccharides,
pubmed-meshheading:3546309-Substrate Specificity
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pubmed:year |
1987
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pubmed:articleTitle |
Purification and properties of a bacteriophage-induced endo-N-acetylneuraminidase specific for poly-alpha-2,8-sialosyl carbohydrate units.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
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