Linked Life Data

1827794

Source:http://linkedlifedata.com/resource/pubmed/id/1827794

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
15
pubmed:dateCreated
1991-6-25
pubmed:abstractText
Tight contact of pyridoxal 5'-phosphate to the substrate phosphate is considered to be a crucial requirement of the phosphorolytic cleavage of polysaccharides by glycogen phosphorylases. This study demonstrates an essential role of lysine 533, the only charged residue in hydrogen bond distance to the phosphate of pyridoxal 5'-phosphate in Escherichia coli maltodextrin phosphorylase. Substitution of Lys533 by Ser reduced the turnover number 600-fold. Addition of monovalent cations significantly increased activity of the Lys533-Ser mutant up to a factor of 10, whereas the apparent affinity for Pi was decreased up to 80-fold. Although substitution of Lys533 by Gln caused a similar reduction of kcat, the Km values remained unchanged, and no response to small cations was observed. These results suggest a key role of the positive charge contributed by Lys533 in catalysis, most probably in maintaining the electrostatic neutrality of the pyridoxal 5'-phosphate and aligning the close phosphate-phosphate contacts indispensable for the proton transfer mechanism.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
266
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
9428-31
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Active site lysine promotes catalytic function of pyridoxal 5'-phosphate in alpha-glucan phosphorylases.
pubmed:affiliation
Department of Physiological Chemistry, University of Würzburg Biozentrum, Federal Republic of Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't