Linked Life Data

3875315

Source:http://linkedlifedata.com/resource/pubmed/id/3875315

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1985-9-3
pubmed:abstractText
Liquefying alpha-amylase from Bacillus amyloliquefaciens was inactivated by treatment with tetranitromethane and N-acetylimidazole. The loss of activity occurred with modification of five tyrosine residues. Preincubation of the enzyme with either the substrate or the competitive inhibitor at saturating levels provided complete protection against inactivation. However, the presence of substrate/inhibitor in the reaction mixture protected only two of the five modifiable tyrosine residues, suggesting the involvement of only two tyrosine residues at the active center. This was confirmed when hydroxylamine treatment of the acetylated enzyme fully restored the enzymatic activity. Both nitration and acetylation increased the apparent Km of the enzyme for soluble starch, which indicated that the tyrosine residues are involved in substrate binding. Reduction of nitrotyrosine residues to aminotyrosine residues failed to restore the enzymatic activity. So, the loss of activity on modification of tyrosine residues was ascribed to conformational perturbances and not simply to the changes in the ionic character of tyrosine residues.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0003-9861
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
240
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
757-67
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1985
pubmed:articleTitle
Chemical modification of liquefying alpha-amylase: role of tyrosine residues at its active center.
pubmed:publicationType
Journal Article