Linked Life Data

8518279

Source:http://linkedlifedata.com/resource/pubmed/id/8518279

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
25
pubmed:dateCreated
1993-7-23
pubmed:abstractText
Myoglobin has been extensively studied as a model system for protein folding in vitro. As part of an ongoing study of myoglobin folding, we have synthesized a series of peptide fragments corresponding to portions of the sequence of the sperm whale protein. The conformational preferences of these peptides have been investigated by circular dichroism and nuclear magnetic resonance spectroscopy in aqueous solution. In this paper we describe the folding propensities of two peptides (Mb-G and Mb-H), corresponding to the G- and H-helix segments of the myoglobin sequence. The Mb-G peptide shows evidence of a very small population of helical conformations in aqueous solution, both by CD and NMR. By contrast, the monomeric Mb-H peptide is found by CD to adopt a significant population (ca. 30%) of ordered helix and by NMR to populate helical conformations in rapid dynamic equilibrium with unfolded states. The Mb-H peptide undergoes a well-characterized, concentration-dependent monomer-tetramer equilibrium. At peptide concentrations greater than 1 mM there is an increase in the population of helix, to approximately 85% according to the CD spectrum, through self-association to form a tetramer. Both medium-range NOE connectivities and a CD spectrum characteristic of ordered helix are observed at low peptide concentrations, establishing that helical conformations are present in the monomeric state of Mb-H. The relative helicity at various sites throughout the Mb-H peptide has been estimated using a novel method for assessing the distribution of helical populations based on the relative magnitudes of medium-range d alpha beta (i,i+3) NOE connectivities. The population of ordered helix is seen to be highest in the center of the peptide sequence; the ends of the peptide show evidence of pronounced fraying.
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
29
pubmed:volume
32
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6337-47
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Peptide models of protein folding initiation sites. 1. Secondary structure formation by peptides corresponding to the G- and H-helices of myoglobin.
pubmed:affiliation
Department of Molecular Biology, Scripps Research Institute, La Jolla, California 92037.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.