Linked Life Data

7011376

Source:http://linkedlifedata.com/resource/pubmed/id/7011376

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1981-6-23
pubmed:abstractText
The diffusion constant of phenylalanyl-tRNA synthetase has been measured by laser light scattering under conditions of complex formation with Mg2+, L-phenylalanine, MgATP, tRNAPhe, modified tRNAPhe, tRNAPhe (yeast), and noncognate tRNA. The diffusion constant (pH 7.5, 20 degrees C) of the free enzyme is (2.85 +/- 0.005) x 10(-7) cm2 s-1, of the enzyme . Mg2+ complex (2.40 +/- 0.05) x 10(-7) cm2 s-1 and of the enzyme . Mg2+ . tRNAPhe complex (2.95 +/- 0.06) x 10(-7) cm2 s-1. The effect of tRNAPhe is only seen when the enzyme is saturated with Mg2+. The smaller substrates exhibit no effect besides a small increase of the value of the diffusion constant under conditions where the enzyme-phenylalanyladenylate is synthesized. Of the noncognate tRNATyr and tRNAIle, the latter is able to associate with the enzyme, causing the value of the diffusion constant to increase. tRNAPhe (yeast) and tRNAhvPhe (photo-cross-linked tRNAPhe) exhibit similar effects. The observed variation of the diffusion constant is attributed to conformational changes of the enzyme. The opposite effects of Mg2+ and tRNAPhe are interpreted as an expansion and recontraction, respectively, of the enzyme molecule. In several cases, the effects were used to follow a titration of the enzyme with a ligand. Dissociation constants were calculated from the resulting titration curves, yielding values which are in agreement with those obtained by other techniques. It is established by comparison that of the two possible binding sites for each Mg2+ and tRNAPhe the diffusion constant reflects occupation of only a single class of sites.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
17
pubmed:volume
20
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
861-7
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1981
pubmed:articleTitle
Detection of ligand-induced conformational changes in phenylalanyl-tRNA synthetase of Escherichia coli K10 by laser light scattering.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't