title: Phenanthrene binding by humic acid-protein complexes as studied by passive dosing technique.
abstract: This work investigated the binding behavior of phenanthrene by humic acids (HA-2 and HA-5), proteins (bovine serum albumin (BSA)), lysozyme and pepsin), and their complexes using a passive dosing technique. All sorption isotherms were fitted well with Freundlich model and the binding capability followed an order of HA-5 > HA-2 > BSA > pepsin > lysozyme. In NaCl solution, phenanthrene binding to HA-BSA complexes was much higher than the sum of binding to individual HA and BSA, while there was no enhancement for HA-pepsin. Positively charged lysozyme slightly lowered phenanthrene binding on both HAs due to strong aggregation of HA-lysozyme complexes, leading to reduction in the number of binding sites. The binding enhancement by HA-BSA was observed under all tested ion species and ionic strengths. This enhancement can be explained by unfolding of protein, reduction of aggregate size and formation of HA-BSA complexes with favorable conformations for binding phenanthrene.
authors.affiliation: Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Wang
authors.forename: Saikat
authors.initials: S
authors.lastname: Ghosh
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing
mesh_terms: D000327:Adsorption; D006632:Histamine / Q000737:chemistry*; D006812:Humic Substances; D008956:Models, Chemical; D010616:Phenanthrenes / Q000737:chemistry*; D011506:Proteins; D012710:Serum Albumin, Bovine / Q000737:chemistry*
chemical_list: D006812:Humic Substances; D010616:Phenanthrenes; D011506:Proteins; C069369:histamine-bovine serum albumin conjugate; D012710:Serum Albumin, Bovine; C031181:phenanthrene; D006632:Histamine
keywords: Atomic force microscopy; Complexation; Dissolved organic matter; Hydrophobic interaction; Hydrophobic organic contaminants