title: Conformational analysis corresponding to intra-chain disulfide bridged peptides in proteins of known three-dimensional structure.
abstract: We have carried out a systematic analysis in order to evaluate whether Intra-Chain Disulfide Bridged Peptides (ICDBPs) observed in proteins of known three-dimensional structure adopt structurally similar conformations as they may correspond to structural/functional motifs. 406 representative ICDBPs comprising between 3 to 17 amino acid residues could be classified according to peptide sequence length and main-chain secondary structure conformation into 146 classes. ICDBPs comprising 6 amino acid residues are maximally represented in the Protein Data Bank. They also represent the maximum number of main-chain secondary structure conformational classes. Individual ICDBPs in each class represent different protein superfamilies and correspond to different amino acid sequences. We identified 145 ICDBP pairs that had not less-than 0.5 A root mean square deviation value corresponding to their equivalent peptide backbone atoms. We believe these ICDBPs represent structural motifs and possible candidates in order to further explore their structure/function role in the corresponding proteins. The common conformational classes observed for ICDBPs defined according to the main-chain secondary structure conformations; H (helix), B (residue in a isolated beta bridge), C (coil), E (extended beta strand), G (3(10) helix), I (pi helix), S (bend), T (hydrogen-bonded turn) were; "CHHH", "CTTC", "CSSS" and "CSSC" (for ICDBP length 4), "CSSCC" (length 5), "EETTEE", "CCSSCC", "CCSSSC" (length 6), "EETTTEE" (length 7), "EETTTTEE" (length 8), "EEEETTEEEE" (length 10), "EEEETTTEEEE" (length 11) and "EEEETTTTEEEE" (length 12).
authors.affiliation: Bioinformatics, Centre for Cellular and Molecular Biology , Hyderabad - 500 007, India.
authors.forename: Settu
authors.initials: S
authors.lastname: Sridhar
authors.forename: Kunchur
authors.initials: K
authors.lastname: Guruprasad
mesh_terms: D000595:Amino Acid Sequence; D030562:Databases, Protein; D004220:Disulfides / Q000737:chemistry*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship
chemical_list: D004220:Disulfides; D010455:Peptides