Ligand cross-linking

The affinity of tannins to bind proteins is favored by their ability to work as multidentate ligands (cross-linking) in which one tannin is able to bind to more than one protein at one time (Fig. 9D.llb) or to bind to more than one point in the same protein (Charlton et al. 2002a Siebert et al. 1996). These associations between tannin and protein could result in aggregates that precipitate depending on the ratio of protein/tannin and also the concentration of protein (Frazier et al. 2003 Poncet-Legrand et al. 2006). 

Holten-Andersen N, Harrington Ml, Birkedal H, Lee BP, Messcusmith PB, Lee KYC, Waite JH (2011) pH-Induced metal-ligand cross-links inspired by mussel yield self-healing polymtu networks with near-covalent elastic moduli. PNAS 108 2651... 

Other chemistries may also be used to reversibly change the properties of hydrogels. Thus, gels with reversible disulfide cross-hnks have been studied [109-111]. Reversible metal-ligand cross-links with a self-repairing function have also been described [112]. Suitable modification of these systems could also be used to form chemically driven actuators. 

Ag(4,4 -bipy)N03 has a three-dimensional structure with silver ions diagonally coordinated by two bipy ligands (N-Ag-N 173.7°) in extended infinite chains, the chains being cross-linked by Ag-Ag bonds (2.970 A) [45]. 

Affinity microparticles (AMPs) were obtained by cross-linking the S-layer lattice on S-layer-carrying cell wall fragments with glutaraldehyde, reducing Schiff bases with sodium borohydride, and immobilizing protein A as an IgG-specific ligand [92]. Thus, AMPs rep-... 

More recently 233) it has been reported that cross-linked polystyrene containing imidazole ligands did not provide a support rigid enough to prevent dimerization, and that the p-oxo dimer was benzene extracted from oxygenated tetraphenyl porphyrin iron(ll), Fe(TPP), which had been attached to the modified polystyrene. A discussion of model synthetic porphyrins, from which definitive structural and other physical data are obtained, is given in section V.C. 

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