Linked Life Data

2108020

Source:http://linkedlifedata.com/resource/pubmed/id/2108020

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1990-5-2
pubmed:abstractText
Functionally important carboxyl groups in glucoamylase G2 from Aspergillus niger were identified using a differential labelling approach which involved modification of the acarbose-inhibited enzyme with 1-ethyl-3-(4-azonia-4,4-dimethylpentyl)carbodiimide (EAC) and inactivation by [3H]EAC following removal of acarbose. Subsequent sequence localization of the substituted acidic residues was facilitated by specific phenylthiohydantoins. The acid cluster Asp176, Glu179 and Glu180 reacted exclusively with [3H]EAC, while Asp112, Asp153, Glu259 and Glu389 had incorporated both [3H]EAC and EAC. It is conceivable that one or two of the [3H]EAC-labelled side chains act in catalysis while the other fully protected residue(s) participates in substrate binding probably together with the partially protected ones. Twelve carboxyl groups that reacted with EAC in the enzyme-acarbose complex were also identified. Asp176, Glu179 and Glu180 are all invariant in fungal glucoamylases. Glu180 was tentatively identified as a catalytic group on the basis of sequence alignments to catalytic regions in isomaltase and alpha-amylase. The partially radiolabelled Asp112 corresponds in Taka-amylase A to Tyr75 situated in a substrate binding loop at a distance from the site of cleavage. A possible correlation between carbodiimide modification of an essential carboxyl group and its role in the glucoamylase catalysis is discussed.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
22
pubmed:volume
188
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
29-38
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Identification of carboxylic acid residues in glucoamylase G2 from Aspergillus niger that participate in catalysis and substrate binding.
pubmed:affiliation
Department of Chemistry, Carlsberg Laboratory, Copenhagen, Denmark.
pubmed:publicationType
Journal Article