title: The SPASIBA force field for chondroitin sulfate: vibrational analysis of D-glucuronic and N-acetyl-D-galactosamine 4-sulfate sodium salts.
abstract: Normal-mode analyses were carried out on the two components of the chondroitin 4-sulfate linear glycosaminoglycan, a copolymer implying alternate D-glucuronate beta-(1-->3) and N-acetyl-D-galactosamine 4-sulfate beta-(1-->4) (hereafter named D-galactosamine 4-sulfate) residues. Scaled quantum mechanical calculations (SQM) using the density functional theory approach at different levels of theory (B3LYP/6-31G** and B3LYP/6-31++G**) were performed to obtain correct vibrational assignments. The SPASIBA empirical force field parameters were then obtained from both theoretical predictions and observed IR and Raman data. It is shown that calculations including diffuse functions at the B3LP/6-31++G** level and the introduction of the Na+ counterion are necessary to give correct assignments of the CO2- symmetric (nu(s)) and antisymmetric (nu(a)) stretching modes for the glucuronic carboxylate residue.
authors.affiliation: Département de Biologie, Faculté des Sciences, Université Abou Bekr Belkaid, 22 rue Abi Ayed Abdelkrim, Faubourg Pasteur, 13000 Tlemcen, Algérie.
authors.forename: M
authors.initials: M
authors.lastname: Meziane-Tani
authors.forename: P
authors.initials: P
authors.lastname: Lagant
authors.forename: A
authors.initials: A
authors.lastname: Semmoud
authors.forename: G
authors.initials: G
authors.lastname: Vergoten
mesh_terms: D000116:Acetylgalactosamine / Q000031:analogs & derivatives* / Q000737:chemistry; D000838:Anions; D002264:Carboxylic Acids / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods*; D002809:Chondroitin Sulfates / Q000737:chemistry*; D020723:Glucuronic Acid / Q000737:chemistry; D008958:Models, Molecular; D008962:Models, Theoretical; D008968:Molecular Conformation; D011108:Polymers / Q000737:chemistry; D011789:Quantum Theory; D012964:Sodium / Q000737:chemistry*; D013053:Spectrophotometry; D014732:Vibration
chemical_list: D000838:Anions; D002264:Carboxylic Acids; D011108:Polymers; C046735:N-acetylgalactosamine 4-sulfate; D020723:Glucuronic Acid; D002809:Chondroitin Sulfates; D012964:Sodium; D000116:Acetylgalactosamine