One-electron oxidation of methionine in peptide environments: The effect of three-electron bonding on the reduction potential of the radical cation

被引:45
作者
Brunelle, P [1 ]
Rauk, A [1 ]
机构
[1] Univ Calgary, Dept Chem, Calgary, AB T2N 1N4, Canada
关键词
D O I
10.1021/jp046626j
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The complexes between the radical cation of dimethyl sulfide 2 and models for eight biologically available electron pair donors, :X (:X = H2O (2a), H2CO (2b), HC(O)NH2 (2c), HC(O)NHCH3 (2d), HCO2- (2e), HCO3- (2f), H2PO4- (2g), and CH3NH2 (2h)), were optimized at the B3LYP/6-31G(d) level of theory. SthereforeX bond dissociation enthalpies (BDEs) were determined by single point calculations at the CBS-RAD level, a method designed for quantitative thermochemistry of free radicals. The effect of solvation was determined by application of a polarizable continuum model. Only the amine complex is predicted to be stable in water. H2O and H2PO4- make transient complexes, and the remaining complexes are predicted to dissociate spontaneously. The dissociation is driven by entropy and conformationally constrained complexes are predicted to be stable in water. Reduction potentials, Edegrees, accurate to +/-0.1 V were calculated for the complexes with dimethyl sulfide and for the amino acid, methionine, both as an isolated amino acid and incorporated into a polypeptide at the N- and C-terminals and midchain. Stabilization of the radical cation of Met by three-electron bonding is predicted if an SthereforeN bond can be formed to a free amino group, as in N-terminal Met or a nearby Lys. Likewise, Met oxidation is facilitated by phosphodiesters, but not by carboxylate groups or amide groups. No lowering of Edegrees is predicted for C-terminal Met or for midchain Met. The implications of the results for the redox chemistry associated with Alzheimer's disease are discussed.
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页码:11032 / 11041
页数:10
相关论文
共 54 条
[1]   RADICAL CATIONS IN MIXTURES OF CL3P AND ME2S - A COMBINED ESR AND QUANTUM CHEMICAL STUDY [J].
AAGAARD, OM ;
DEWAAL, BFM ;
CABBOLET, MJTF ;
JANSSEN, RAJ .
JOURNAL OF PHYSICAL CHEMISTRY, 1992, 96 (02) :614-623
[2]   INCORPORATION OF SOLVENT EFFECTS INTO DENSITY-FUNCTIONAL CALCULATIONS OF MOLECULAR-ENERGIES AND GEOMETRIES [J].
ANDZELM, J ;
KOLMEL, C ;
KLAMT, A .
JOURNAL OF CHEMICAL PHYSICS, 1995, 103 (21) :9312-9320
[3]  
Armstrong DA, 1999, CHEM FREE RADICALS, P27
[4]   Mechanism of one-electron oxidation of beta-, gamma-, and delta-hydroxyalkyl sulfides. Catalysis through intramolecular proton transfer and sulfur-oxygen bond formation [J].
Bobrowski, K ;
Hug, GL ;
Marciniak, B ;
Miller, B ;
Schoneich, C .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1997, 119 (34) :8000-8011
[5]   A systematic failing of current density functionals:: Overestimation of two-center three-electron bonding energies [J].
Braïda, B ;
Hiberty, PC ;
Savin, A .
JOURNAL OF PHYSICAL CHEMISTRY A, 1998, 102 (40) :7872-7877
[6]   Stability, metastability, and unstability of three-electron-bonded radical anions.: A model ab initio theoretical study [J].
Braïda, B ;
Thogersen, L ;
Wu, W ;
Hiberty, PC .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2002, 124 (39) :11781-11790
[7]   Methyl substituent effects in [HnX∴XHn]+ three-electron-bonded radical cations (X=F, O, N, Cl, S, P; n=1-3).: An ab initio theoretical study [J].
Braïda, B ;
Hazebroucq, S ;
Hiberty, PC .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2002, 124 (10) :2371-2378
[8]   Diatomic halogen anions and related three-electron-bonded anion radicals:: Very contrasted performances of Moller-Plesset methods in symmetric vs dissymmetric cases [J].
Braïda, B ;
Hiberty, PC .
JOURNAL OF PHYSICAL CHEMISTRY A, 2000, 104 (19) :4618-4628
[9]  
Braïda B, 2001, J CHEM PHYS, V115, P90, DOI 10.1063/1.1373427
[10]   Methionine residue 35 is critical for the oxidative stress and neurotoxic properties of Alzheimer's amyloid β-peptide 1-42 [J].
Butterfield, DA ;
Kanski, J .
PEPTIDES, 2002, 23 (07) :1299-1309