Linked Life Data

11714271

Source:http://linkedlifedata.com/resource/pubmed/id/11714271

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
47
pubmed:dateCreated
2001-11-20
pubmed:abstractText
The relation between the quaternary structure and the substrate specificity of Thermus maltogenic amylase (ThMA) has been investigated. Sedimentation diffusion equilibrium ultracentrifugation and gel filtration analyses, in combination with the crystal structure determined recently, have demonstrated that ThMA existed in a monomer/dimer equilibrium. The truncation of ThMA by removing the N-terminal domain, which is composed of 124 amino acid residues, resulted in the complete monomerization of the enzyme (ThMADelta124) accompanied by a drastic decrease in the activity for beta-cyclodextrin (beta-CD) and a relatively smaller reduction of the activity for starch. Despite the overall low activity of ThMADelta124, the activity was higher toward starch than beta-CD, and the ratio of the specific activities toward these substrates was approximately 100 fold higher than that of wild-type ThMA. Furthermore, the addition of KCl to wild-type ThMA shifted the monomer/dimer equilibrium toward the monomer. In the presence of 1.0 M KCl, the relative activity of ThMA toward beta-CD decreased to 74%, while that for soluble starch increased to 194% compared to the activities in the absence of KCl. Thus, the ThMA monomer and dimer are both inferred to be enzymatically active but with a somewhat different substrate preference. Kinetic parameters of the wild-type and truncated enzymes also are in accordance with the changes in their specific activities. We thus provide evidence in support of a model, which shows that the relative multisubstrate specificity of ThMA is influenced by the monomer/dimer equilibrium of the enzyme.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
27
pubmed:volume
40
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
14182-90
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:11714271-Amino Acid Sequence, pubmed-meshheading:11714271-Centrifugation, Isopycnic, pubmed-meshheading:11714271-Cyclodextrins, pubmed-meshheading:11714271-Dimerization, pubmed-meshheading:11714271-Glycoside Hydrolases, pubmed-meshheading:11714271-Kinetics, pubmed-meshheading:11714271-Models, Molecular, pubmed-meshheading:11714271-Molecular Sequence Data, pubmed-meshheading:11714271-Mutation, pubmed-meshheading:11714271-Osmolar Concentration, pubmed-meshheading:11714271-Peptide Fragments, pubmed-meshheading:11714271-Protein Structure, Quaternary, pubmed-meshheading:11714271-Sequence Deletion, pubmed-meshheading:11714271-Starch, pubmed-meshheading:11714271-Substrate Specificity, pubmed-meshheading:11714271-Symporters, pubmed-meshheading:11714271-Thermus, pubmed-meshheading:11714271-beta-Cyclodextrins
pubmed:year
2001
pubmed:articleTitle
Modulation of the multisubstrate specificity of Thermus maltogenic amylase by truncation of the N-terminal domain and by a salt-induced shift of the monomer/dimer equilibrium.
pubmed:affiliation
Research Center for New Bio-Materials in Agriculture and Department of Food Science & Technology, School of Agricultural Biotechnology, Seoul National University, Suwon 441-744, Korea.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't