کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5559362 | 1561575 | 2017 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Cd2+ and Pb2+ complexation by glutathione and the phytochelatins
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کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
علوم محیط زیست
بهداشت، سم شناسی و جهش زایی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Phytochelatins or PCn, (γGlu-Cys)n-Gly, and their glutathione (GSH) precursor are thiol-rich peptides that play an important role in heavy metal detoxification in plants and microorganisms. Complex formation between Cd2+ and Pb2+ and GSH or PCn (n = 2, 4 and 6) are investigated by microcalorimetry, absorption spectrophotometry and T-jump kinetics. Complex formation with Pb2+ or Cd2+ is exothermic, and induces ligand metal charge transfer bands in UV absorption spectral range, which implies the formation of a coordination bond between the metal and the thiol groups of the phytochelatins. Absorption spectra and microcalorimetry experiments allow the determination of the affinity constants and the stoichiometry of the complexes. We show that the three PCn interact with Pb2+ to form the 1:1 and 2:1 M:L complexes, with similar affinity constants (log K11Pbâ¼4.6, log K21Pbâ¼11.4). These affinities are independent of the number of thiols and are, moreover, lower than those determined for complex formation with Cd2+. On the other hand, with Cd2+, PC2-Cd, PC2-Cd2, (PC2)3-Cd2, PC4-Cd, PC4-Cd2, PC6-Cd, (PC6)2-Cd3 and PC6-Cd3 complexes are detected. Furthermore, for PC4-Cd, the 1:1 complex is the most stable: affinity constant (log K11Cdâ¼7.5). Kinetic studies indicate that complex formation between Cd2+ and GSH occurs in the ms range; direct rate constant kobs = (6.8 ± 0.3) 106 Mâ1 sâ1 and reverse rate constant kâobs = 340 ± 210 sâ1. Thus, when encapsulated in a silica matrix, PCn can be good candidates for heavy metal detection.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemico-Biological Interactions - Volume 267, 1 April 2017, Pages 2-10
Journal: Chemico-Biological Interactions - Volume 267, 1 April 2017, Pages 2-10
نویسندگان
Aurélie Jacquart, Roberta Brayner, Jean-Michel El Hage Chahine, Nguyet-Thanh Ha-Duong,