Linked Life Data

1856235

Source:http://linkedlifedata.com/resource/pubmed/id/1856235

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
21
pubmed:dateCreated
1991-8-23
pubmed:abstractText
malQ mutants, lacking amylomaltase, cannot grown on maltose. However, when maltose is present in the medium, it can be accumulated to high internal levels. In a subsequent slow reaction, accumulated maltose becomes acetylated and leaks back into the medium. The enzyme responsible for this acetylation uses acetyl-CoA as acetyl donor and can be measured in crude extracts (Boos, W., Ferenci, T., and Shuman, H. A. (1981) J. Bacteriol. 146, 725-732). The structural gene for the enzyme, which we named mac, was mapped at 10.4 min on the Escherichia coli linkage map. We cloned a 3.4-kilobase pair PstI-EcoRI DNA fragment containing the mac gene. Cell-free extracts of a strain harboring the multicopy plasmid were used to purify the maltose-transacetylating activity to apparent homogeneity. On sodium dodecyl sulfate-polyacrylamide gels the enzyme exhibited a molecular weight of 20,000. Using molecular sieve chromatography, a molecular weight of 40,000 was determined for the native enzyme. Therefore, the enzyme is a dimer of two identical subunits. At a sugar concentration of 100 mM the enzyme acetylates glucose, maltose, mannose, galactose, and fructose in decreasing relative rate of 1, 0.55, 0.20, 0.07, 0.04. Maltotriose and other oligosaccharides were acetylated with 2% of the rate determined for glucose. The Km for glucose and maltose were 62 and 90 mM, and the Vmax was 0.20 and 0.11 mmol/min x mg enzyme, respectively.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
266
pubmed:geneSymbol
mac
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
14113-8
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Maltose transacetylase of Escherichia coli. Mapping and cloning of its structural, gene, mac, and characterization of the enzyme as a dimer of identical polypeptides with a molecular weight of 20,000.
pubmed:affiliation
Department of Biology, University of Konstanz, Federal Republic of Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't