Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1977-5-12
pubmed:abstractText
The primary structure of collagen is characterized by the repeating tripeptide sequence (Gly-R2-R3)n. The results of theoretical studies, carried out using contact criteria to compute the stereochemically allowed orientations for various side chains at locations 2 and 3, are reported here. It is found that side chains with only gamma-atoms, as in valine, serine and threonine, or with only one delta-methyl group, as in isoleucine, can occur equally well at locations 2 and 3, as is actually the case in collagen. Side chains with two Cdelta-atoms, as in leucine and phenylalanine, can also be accommodated at both positions. However, if they occur as R3, their freedom of orientation is severely restricted in the presence of a proline residue as R2 in a neighbouring chain. If water molecules bound to the chains of the triple helix are assumed to be present, then location 3 is virtually impossible for leucine and phenylalanine residues. Location 2 is, however, unaffected, and their presence as R2 can help to shield the water molecules from disturbance by the solvent medium. This may be the reason for the preferential occurrence of Leu and Phe residues in location 2 in the collagen triplets, although the polypeptides (Gly-Pro-Leu)n and (Gly-Pro-Phe)n form collagen-like structures.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0367-8377
pubmed:author
pubmed:issnType
Print
pubmed:volume
9
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
224-34
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1977
pubmed:articleTitle
Stereochemical restrictions on the occurrence of amino acid residues in the collagen structure.
pubmed:publicationType
Journal Article