Premium
The role of Ni(II) in the oxidation of glycylglycine dipeptide by peroxomonosulfatex
Author(s) -
Thendral P.,
Shailaja S.,
Ramachandran M. S.
Publication year - 2009
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.20360
Subject(s) - glycylglycine , chemistry , dipeptide , kinetics , medicinal chemistry , protonation , peroxide , inorganic chemistry , reaction rate constant , catalysis , ion , organic chemistry , glycine , amino acid , biochemistry , physics , quantum mechanics
The kinetics of oxidation of the dipeptide glycylglycine by peroxomonosulfate (PMS) was studied in the pH range of 3.42–5.89. The rate is first order in [PMS], glycylglycine concentration, and inverse first order in [H + ]. The kinetic data suggest that SO 2− 5 reacts, with glycylglycine, faster than HSO − 5 by five orders of magnitude. The observed kinetics can be explained as due to the formation of an intermediate by the nucleophilic interaction of peroxide with the terminal protonated amine of glycylglycine, which then decomposes in the rate‐limiting step to the product aldehyde. The thermodynamic parameters are evaluated. The reaction is catalyzed by Ni(II) ions only when pH ⩽ 4.63, and above this pH the rate is zero order with respect to [Ni(II)]. Perusal of the enhanced rate constant values suggests that the Ni‐peroxide intermediate also reacts with glycylglycine. The Ni‐dipeptide complex is not oxidized by PMS, and this complex in fact inhibits the formation of Ni‐peroxide intermediate. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 18–26, 2009