Linked Life Data

12056889

Source:http://linkedlifedata.com/resource/pubmed/id/12056889

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
24
pubmed:dateCreated
2002-6-11
pubmed:abstractText
To explore electrostatic interactions in ubiquitin, pK(a) values have been determined by NMR for all 12 carboxyl groups in wild-type ubiquitin and in variants where single lysines have been replaced by neutral residues. Aspartate pK(a) values in ubiquitin range from 3.1 to 3.8 and are generally less than model compound values. Most aspartate pK(a) values are within 0.2 pH unit of those predicted with a simple Tanford-Kirkwood model. Glutamate pK(a) values range from 3.8 to 4.5, close to model compound values and differing by 0.1-0.8 pH unit from calculated values. To determine the role of positive charges in modulating carboxyl pK(a) values, we mutated lysines at positions 11, 29, and 33 to glutamine and threonine. NMR studies with these six single-site mutants reveal significant interactions of Lys 11 and Lys 29 with Glu 34 and Asp 21, respectively: pK(a) values for Glu 34 and Asp 21 increase by approximately 0.5-0.8 pH unit, similar to predicted values, when the lysines are replaced by neutral residues. In contrast, the predicted interaction between Lys 33 and Glu 34 is not observed experimentally. In some instances, substitution of lysine by glutamine and threonine did not lead to the same changes in carboxyl pK(a) values. These may reflect new short-range interactions between the mutated residues and the carboxyl groups. Carboxyl pK(a) shifts > 0.5 pH unit result from mutations at groups that are <5 A from the carboxyl group. No interactions are observed at >10 A.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
18
pubmed:volume
41
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
7586-96
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
Electrostatic interactions in ubiquitin: stabilization of carboxylates by lysine amino groups.
pubmed:affiliation
Department of Biochemistry, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't