title: Chelation of vanadium(IV) by a natural and edible biopolymer poly(gamma-glutamic acid) in aqueous solution: structure and binding constant of complex.
abstract: The naturally occurring edible biopolymer poly(gamma-glutamic acid) (gamma-PGA) is shown to be an efficient chelating agent of vanadium(IV). The structure of poly(gamma-glutamic acid)oxovanadium(IV) (VO-gamma-PGA) complex in solution has been analyzed by electron spin resonance and UV-visible absorption spectra. The equatorial coordination sphere of vanadium(IV) is proposed to be [2 x carboxylate (2O)-VO-(OH2)2]. The binding isotherm is determined for suspensions of gamma-PGA in vanadium(IV) oxide sulfate (VS) solutions of different concentrations, and the data have been adjusted to fit the modified Langmuir equation. The maximum amount of vanadium bound per gram of gamma-PGA is estimated to be 141 mmol . g(-1) with a binding constant of 22 L . g(-1) at pH 3.
authors.affiliation: Department of Analytical and Bioinorganic Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan.
authors.forename: Subarna
authors.initials: S
authors.lastname: Karmaker
authors.forename: Tapan K
authors.initials: TK
authors.lastname: Saha
mesh_terms: D002614:Chelating Agents / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry*; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D014639:Vanadium / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D002614:Chelating Agents; D046911:Macromolecular Substances; C511775:poly(gamma-glutamic acid); D014639:Vanadium; D014867:Water; D011099:Polyglutamic Acid