Linked Life Data

2806252

Source:http://linkedlifedata.com/resource/pubmed/id/2806252

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1989-12-5
pubmed:abstractText
The surface topography of aromatic amino acid residues and/or other hydrophobic groups of phytochrome has been investigated by ultraviolet absorption spectra and ultraviolet circular dichroism using phytochrome-cyclodextrin inclusion complexation. Three different types of cyclodextrins (alpha, beta and gamma) with varying hydrophobic cavity sizes, were used. Complexation resulted in significant changes in the circular dichroic signals of both the red-light-absorbing (Pr) and far-red-light-absorbing (Pfr) forms of phytochrome in the ultraviolet region at 222 nm, mid-ultraviolet at 280 nm and 300 nm and in the near-ultraviolet and visible regions at 365 nm and 670 mm, respectively, alpha- and beta-Cyclodextrins were markedly (1.7-4.5-fold) more effective in reducing the mid-ultraviolet CD signal of Pr than that of Pfr, indicating a differential inclusion of the aromatic amino acid residues. gamma-Cyclodextrin did not exhibit any significant differentiation. Secondary structure analysis of the phytochrome-cyclodextrin complexes revealed a considerable increase in the alpha-helical contents of both Pr and Pfr forms. The increase in the Pfr form (17-25%) was about twice that in the Pr form (8-9%), indicating a differential effect of complexation on the conformation of the phytochrome protein. Although the photostationary-state equilibrium of the phytochrome was not affected by the cyclodextrin complexation, the Pr----Pfr phototransformation rate was significantly increased. However, the Pfr----Pr photoreversion was not affected significantly. The results suggest a differential complexation of cyclodextrins with the Pr and Pfr forms of phytochrome as a result of a difference in accessibility of aromatic amino acids in the two forms. A detailed analysis of absorption difference spectra and circular dichroic spectra around 280 nm also revealed evidence for a difference in the exposure of aromatic amino acids.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
184
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
715-21
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Differential exposure of aromatic amino acids in the red-light-absorbing and far-red-light-absorbing forms of 124-kDa oat phytochrome.
pubmed:affiliation
Department of Chemistry, School of Biological Sciences, University of Nebraska, Lincoln.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't