References of "Proteins-Structure Function and Genetics"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailAromatic Side-Chain Interactions In Proteins: Near- And Far-Sequence Tyr-X Pairs
Meurisse, R.; Brasseur, Robert ULg; Thomas, Annick ULg

in Proteins-Structure Function and Genetics (2004), 54(3), 478-90

In the present study, an extensive analysis of the aromatic Tyr-X interactions is performed on a data set of 593 PDB structures, X being Phe, His, Tyr, and Trp. The nonredundant Tyr-X pairs (2645) were ... [more ▼]

In the present study, an extensive analysis of the aromatic Tyr-X interactions is performed on a data set of 593 PDB structures, X being Phe, His, Tyr, and Trp. The nonredundant Tyr-X pairs (2645) were retained and separated by both the residue distance in the sequence and the secondary structures they bridge. Similar to the Phe-X and His-X pairs, the far-sequence Tyr-X pairs (X partner > five apart in the sequence: 74%) show comparable secondary structures and conformers for either type of X partner, in contrast with the near-sequence Tyr-X pairs (26%). As the Phe-X pairs, the near-sequence Tyr-X pairs stabilize secondary structures, mainly the alpha- helices (positions 1, 3, and 4) and the beta-strands (position 2). Like the Phe-X and His-X pairs, most far-sequence Tyr-X pairs (34%) bridge beta-strands and only 11% bridge helices. As for the Phe-X and the His-X pairs, the X partners of the far-sequence Tyr-X pairs are frequently "above" the tyrosine ring with tilted and normal rings, whereas the X partner of the near-sequence Tyr-X pairs gradually moves from the "aside" to the "above" location, together with a progressive decrease of normal and increase of parallel rings, respectively. Unlike the His-X pairs, the interactions of the hetroatom in Tyr-X pairs are only favored with a sequence position +4 and over, owing to the spatial accessibility of the heteroatom. [less ▲]

Detailed reference viewed: 2 (0 ULg)
Full Text
Peer Reviewed
See detailAromatic Side-Chain Interactions In Proteins. II. Near- And Far-Sequence Phe-X Pairs
Thomas, Annick ULg; Meurisse, R.; Brasseur, Robert ULg

in Proteins-Structure Function and Genetics (2002), 48(4), 635-44

We have collected all aromatic pairs (3152) involving an N-phenyl partner in a dataset of 593 proteins of the PDB: 728 of these pairs involve a partner residue less than 6 apart in the sequence. These ... [more ▼]

We have collected all aromatic pairs (3152) involving an N-phenyl partner in a dataset of 593 proteins of the PDB: 728 of these pairs involve a partner residue less than 6 apart in the sequence. These near-sequence Phe-X pairs correspond to specific conformations that stabilize secondary structures, mainly alpha-helices when the residues are 1, 3, and 4 apart, and beta-strands when they are 2 apart in the sequence. These conformations are not spatially random and have been examined in detail. The remaining phenylalanine pairs (2424) are between partners more than 5 apart in the sequence. Of these far-sequence pairs, 34% of occurrences are in sheets. Next in frequencies are pairs that bridge a beta-strand to a helix (24%), followed by pairs that bridge a beta-strand to a random coiled structure (15%). Helix to helix pairs only constitute 12% of these far-sequence pairs. Analysis of the pairing frequency supports the hypothesis that aromatic interactions are late events of protein folding. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailAromatic Side-Chain Interactions In Proteins. I. Main Structural Features
Thomas, Annick ULg; Meurisse, R.; Charloteaux, Benoît ULg et al

in Proteins-Structure Function and Genetics (2002), 48(4), 628-34

In a data set of 593 nonhomologous proteins from the PDB, we have analyzed the pairing of phenylalanine, tyrosine, tryptophan, and histidine residues with their closest aromatic partner. The frequency ... [more ▼]

In a data set of 593 nonhomologous proteins from the PDB, we have analyzed the pairing of phenylalanine, tyrosine, tryptophan, and histidine residues with their closest aromatic partner. The frequency distribution of the shortest interatomic distance of partners is bimodal with a sharp peak at approximately 3.8 A and a wider one at a longer distance. Only the 3.8 A peak corresponds to direct ring-ring interactions thus aromatic pairs. The aromatic pairs were separated into two classes, near-sequence pairs and far-sequence pairs. Near sequence pairs stabilize local structure, and far-sequence pairs stabilize tertiary structure. Far-sequence pairs (74% of all pairs) mainly bridge two beta-strands, followed by pairs that bridge a beta-strand and a helix, and pairs that bridge a beta-strand and a random coil structure. Pairs that bridge helices are rare. The secondary structure of the near-sequence pairs depends on the partner distance in the sequence. When the partners are 1, 3, or 4 residues apart in the sequence, pairs are mostly found in helical structures. When the partners are two apart, pairs are mostly found in the same beta-strand. Analysis of the frequency of near sequence pairs supports the hypothesis that aromatic pairing occurs after, rather than before, the formation of secondary structures. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailPex, Analytical Tools For Pdb Files. II. H-Pex: Noncanonical H-Bonds In Alpha-Helices
Thomas, Annick ULg; Benhabiles, N.; Meurisse, R. et al

in Proteins-Structure Function and Genetics (2001), 43(1), 37-44

We use the H-Pex (Thomas et al., this issue) to analyze the main chain interactions in 131 proteins. In antiparallel beta-sheets, the geometry of the N...O bond is: median N...O distances, 2.9 SA, C==O ... [more ▼]

We use the H-Pex (Thomas et al., this issue) to analyze the main chain interactions in 131 proteins. In antiparallel beta-sheets, the geometry of the N...O bond is: median N...O distances, 2.9 SA, C==O...N angles at 154 degrees and the C alpha--C==O...H angles are dispersed around 3 degrees. In some instances, the other side of the C==O axis is occupied by a HC alpha. As recently supported by Vargas et al. (J Am Chem Soc 2000;122:4750-4755) C alpha H...O and NH...O could cooperate to sheet stability. In alpha-helices, the main chain C==O interact with the NH of their n + 4 neighbor on one side, and with a C beta H or C gamma H on the other side. The median O...N distance (3.0 A) and C==N angle (147 degrees) suggest a canonical H-bond, but the C alpha--C==O...H dihedral angle invalidates this option, since the hydrogen attacks the oxygen at 122 degrees, i.e., between the sp(2) and pi orbitals. This supports that the H-bond is noncanonical. In many instances, the C gamma H or the C beta H of the n + 4 residue stands opposite to the NH with respect to the oxygen. Therefore, we propose that, in alpha-helices, the C gamma H or C beta H and the NH of the n + 4 residue hold the oxygen like an electrostatic pincher. [less ▲]

Detailed reference viewed: 7 (0 ULg)
Full Text
Peer Reviewed
See detailPex, Analytical Tools For Pdb Files. I. Gf-Pex: Basic File To Describe A Protein
Thomas, Annick ULg; Bouffioux, O.; Geeurickx, D. et al

in Proteins-Structure Function and Genetics (2001), 43(1), 28-36

Pex are created to extract numeric and string descriptions of protein structures from PDB files. This concerns covalent bond lengths and angles, secondary structures, residues in interaction, H-bond ... [more ▼]

Pex are created to extract numeric and string descriptions of protein structures from PDB files. This concerns covalent bond lengths and angles, secondary structures, residues in interaction, H-bond lengths and geometry, etc. Several kinds of Pex are generated: (1) general feature (GF-Pex); (2) H-bond (H-Pex); and (3) accessible surface (AS-Pex) and force potential (FP-Pex). We describe the general principles of Pex and detail the GF-Pex files. Using the GF-Pex of 131 proteins, we analyze the mean residue frequencies, the straight phi/psi distribution and the major kinds of secondary structures in proteins. Thomas et al. (this issue) analyzes the main chain H-bonds in those proteins. The GF-Pex and H-Pex files of the 131 proteins can be downloaded from the CBMN site (http://www.fsagx.ac.be/bp/). [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailComputational Study Of Lipid-Destabilizing Protein Fragments: Towards A Comprehensive View Of Tilted Peptides
Lins, Laurence ULg; Charloteaux, Benoît ULg; Thomas, Annick ULg et al

in Proteins-Structure Function and Genetics (2001), 44(4), 435-47

Tilted peptides are short sequence fragments (10-20 residues long) that possess an asymmetric hydrophobicity gradient along their sequence when they are helical. Due to this gradient, they adopt a tilted ... [more ▼]

Tilted peptides are short sequence fragments (10-20 residues long) that possess an asymmetric hydrophobicity gradient along their sequence when they are helical. Due to this gradient, they adopt a tilted orientation towards a single lipid/water interface and destabilize the lipids. We have detected those peptides in many different proteins with various functions. While being all tilted-oriented at a single lipid/water interface, no consensus sequence can be evidenced. In order to better understand the relationships between their lipid-destabilizing activity and their properties, we used IMPALA to classify the tilted peptides. This method allows the study of interactions between a peptide and a modeled lipid bilayer using simple restraint functions designed to mimic some of the membrane properties. We predict that tilted peptides have access to a wide conformational space in membranes, in contrast to transmembrane and amphipathic helices. In agreement with previous studies, we suggest that those metastable configurations could lead to the perturbation of the acyl chains organization and could be a general mechanism for lipid destabilization. Our results further suggest that tilted peptides fall into two classes: those from proteins acting on membrane behave differently than destabilizing fragments from interfacial proteins. While the former have equal access to the two layers of the membrane, the latter are confined within a single lipid layer. This could be in relation with the organization of lipid substrate on which the peptides physiologically act. [less ▲]

Detailed reference viewed: 9 (5 ULg)