title: Density functional theory study on the cross-linking of mussel adhesive proteins.
abstract: The water-resistant adhesion of mussel adhesive proteins (MAPs) to a wet surface requires a cross-linking step, where the catecholic ligands of MAPs coordinate to various transition-metal ions. Fe(III), among the range of metal ions, induces particularly strong cross-linking. The molecular details underlying this cross-linking mediated by transition-metal ions are largely unknown. Of particular interest is the metal-ligand binding energy, which is the molecular origin of the mechanical properties of cross-linked MAPs. Using density functional theory, this study examined the structures and binding energies of various trivalent metal ions (Ti-Ga) forming coordination complexes with a polymeric ligand similar to a MAP. These binding energies were 1 order of magnitude larger than the physisorption energy of a catechol molecule on a metallic surface. On the other hand, the coordination strength of Fe(III) with the ligand was not particularly strong compared to the other metal ions studied. Therefore, the strong cross-linking in the presence of Fe(III) is ascribed to its additional ability as an oxidant to induce covalent cross-linking of the catecholic groups of MAPs.
authors.forename: Mohammad A
authors.initials: MA
authors.lastname: Matin
authors.forename: Ramesh Kumar
authors.initials: RK
authors.lastname: Chitumalla
authors.forename: Manho
authors.initials: M
authors.lastname: Lim
authors.affiliation: §CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Xingfa
authors.initials: X
authors.lastname: Gao
authors.forename: Joonkyung
authors.initials: J
authors.lastname: Jang
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry / Q000494:pharmacology*; D004295:Dihydroxyphenylalanine / Q000737:chemistry; D008024:Ligands; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry / Q000494:pharmacology*; D011487:Protein Conformation; D055550:Protein Stability; D011506:Proteins / Q000737:chemistry*; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: D003432:Cross-Linking Reagents; D008024:Ligands; D009942:Organometallic Compounds; D011506:Proteins; C037403:adhesive protein, mussel; D004295:Dihydroxyphenylalanine