Linked Life Data

16783793

Source:http://linkedlifedata.com/resource/pubmed/id/16783793

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2006-8-21
pubmed:abstractText
The 3(10)-helix is characterized by having at least two consecutive hydrogen bonds between the main-chain carbonyl oxygen of residue i and the main-chain amide hydrogen of residue i + 3. The helical parameters--pitch, residues per turn, radius, and root mean square deviation (rmsd) from the best-fit helix--were determined by using the HELFIT program. All 3(10)-helices were classified as regular or irregular based on rmsd/(N - 1)1/2 where N is the helix length. For both there are systematic, position-specific shifts in the backbone dihedral angles. The average phi, psi shift systematically from approximately -58 degrees, approximately -32 degrees to approximately -90 degrees, approximately -4 degrees for helices 5, 6, and 7 residues long. The same general pattern is seen for helices, N = 8 and 9; however, in N = 9, the trend is repeated with residues 6, 7, and 8 approximately repeating the phi, psi of residues 2, 3, and 4. The residues per turn and radius of regular 3(10)-helices decrease with increasing length of helix, while the helix pitch and rise per residue increase. That is, regular 3(10)-helices become thinner and longer as N increases from 5 to 8. The fraction of regular 3(10)-helices decreases linearly with helix length. All longer helices, N > or = 9 are irregular. Energy minimizations show that regular helices become less stable with increasing helix length. These findings indicate that the definition of 3(10)-helices in terms of average, uniform dihedral angles is not appropriate and that it is inherently unstable for a polypeptide to form an extended, regular 3(10)-helix. The 3(10)-helices observed in proteins are better referred to parahelices.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
1097-0134
pubmed:author
pubmed:issnType
Electronic
pubmed:day
15
pubmed:volume
64
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
691-9
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
3(10)-helices in proteins are parahelices.
pubmed:affiliation
Division of Biological Resources and Production, Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't