Linked Life Data

436009

Source:http://linkedlifedata.com/resource/pubmed/id/436009

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1979-7-28
pubmed:abstractText
The structural features of the native Ca2+-dependent protein modulator and two chemically modified derivatives, namely, nitrotyrosyl modulator and alkylated modulator, were examined by circular dichroism. The binding of Ca2+ to the native molecule was accompanied by an increase in helical content from 40 to 49%, with little effect on the local environments of aromatic residues in the modulator. The Mg2+ and Mn2+ do not elicit the conformational change induced by the binding of Ca2+, which also stabilizes the modulator against urea denaturation. The overall secondary structure of nitrotyrosyl modulator is indistinguishable from that of the native protein and undergoes a similar conformational change upon binding Ca2+. These observations are in agreement with the fact that nitration has no effect on modulator functions. Furthermore, nitrotyrosyl modulator interacts with troponin I only in the presence of Ca2+, as detected by circular dichroism (cd). On the other hand, alkylation of five methionine residues on the modulator with benzyl bromide affects protein conformation, as evidenced by a reduced helical content of only 35%. Alkylated modulator retains the ability of the native protein to bind Ca2+ although the affinity of this derivative for Ca2+ is reduced some three orders of magnitude relative to the native protein, with Kd = 3.2 X 10(-4) M. The results with the alkylated modulator, in conjunction with previous cd studies on N-chlorosuccinimide oxidized modulator are utilized to advance a model for the Ca2+ activation of modulator protein, based on three conformational states of the molecule.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0008-4018
pubmed:author
pubmed:issnType
Print
pubmed:volume
57
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
267-78
pubmed:dateRevised
2000-12-18
pubmed:meshHeading
pubmed:year
1979
pubmed:articleTitle
Circular dichroism studies of native and chemically modified Ca2+-dependent protein modulator.
pubmed:publicationType
Journal Article