title: The interaction of chromium(VI) with urease in solution.
abstract: The interaction between K(2)Cr(2)O(7) and urease was investigated using fluorescence, UV-vis absorption, and circular dichroism (CD) spectroscopy. The experimental results showed that the fluorescence quenching of urease by K(2)Cr(2)O(7) was a result of the formation of K(2)Cr(2)O(7)-urease complex. The apparent binding constant K (A) between K(2)Cr(2)O(7) and urease at 295, 302, and 309 K were obtained to be 2.14 × 10(4), 1.96 × 10(4), and 1.92 × 10(4) L mol(-1), respectively. The thermodynamic parameters, ΔH° and ΔS° were estimated to be -5.90 kJ mol(-1), 43.67 J mol(-1) K(-1) according to the Van't Hoff equation. The electrostatic interaction played a major role in stabilizing the complex. The distance r between donor (urease) and acceptor (K(2)Cr(2)O(7)) was 5.08 nm. The effect of K(2)Cr(2)O(7) on the conformation of urease was analyzed using UV-vis absorption, CD, synchronous fluorescence spectroscopy, and three-dimensional fluorescence spectra, the environment around Trp and Tyr residues were altered.
authors.affiliation: Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, Yancheng City, Jiangsu Province, 224002, People's Republic of China.
authors.forename: Hong-Mei
authors.initials: HM
authors.lastname: Zhang
authors.forename: Gen-Cheng
authors.initials: GC
authors.lastname: Zhang
authors.forename: Yan-Qing
authors.initials: YQ
authors.lastname: Wang
mesh_terms: D002840:Chromates / Q000737:chemistry*; D002942:Circular Dichroism; D004735:Energy Transfer; D005453:Fluorescence; D017680:Potassium Compounds / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D014510:Urease / Q000737:chemistry / Q000378:metabolism*
chemical_list: D002840:Chromates; D017680:Potassium Compounds; C027373:potassium chromate(VI); D014510:Urease