The Na+ affinities of α-amino acids:: side-chain substituent effects

被引:147
作者
Kish, MM
Ohanessian, G
Wesdemiotis, C [1 ]
机构
[1] Univ Akron, Dept Chem, Akron, OH 44325 USA
[2] Ecole Polytech, Lab Mecanismes React, UMR 7651, CNRS, F-91128 Palaiseau, France
基金
美国国家科学基金会;
关键词
amino acids; sodium ion affinities; kinetic method; charge solvation; salt bridge;
D O I
10.1016/S1387-3806(03)00082-4
中图分类号
O64 [物理化学(理论化学)、化学物理学]; O56 [分子物理学、原子物理学];
学科分类号
070203 ; 070304 ; 081704 ; 1406 ;
摘要
Na+-bound heterodimers of amino acids (AA) are produced in the gas phase by electrospray ionization (ESI). The dissociation kinetics of these AA(1)-Na+-AA(2) ions are determined by collisionally activated dissociation (CAD) and converted to a ladder of relative Na+ affinities via the Cooks kinetic method. The affinities derived follow the order (kJ mol(-1), relative to Gly): Gly (0), Ala (6), Val (12), Leu (13), Cys (14), Ile (15), Ser (31), Pro (35), Thr (36), Phe (37), Tyr (40), Asp (42), Glu (43), Asn (45), Trp (49), Gln (51), His (57). Absolute Na+ binding energies are estimated by anchoring the relative values to the Na+ affinity of Ala (167 0 mol(-1)), measured by the same approach using Na+-bound dimers of Ala and a series of acetamide derivatives. The Na+ binding energies of the acetamide reference bases and of representative aliphatic and side-chain functionalized amino acids (Gly, Ala, Pro, Cys and Ser) are determined by ab initio theory. Experimental and ab initio affinities agree very well. The combined data show that functional side chains increase the AA-Na+ bond strength by providing an extra ligand to the metal ion. Aromatic and carbonyl substituents in the side chain bring about substantial increases in the Na+ binding energy, with particularly large increments observed for amide and electron-rich (N-containing) aromatic groups. A poor correlation is found between sodium ion and proton affinities, strongly suggesting that the Na+ complexes do not have salt-bridge structures involving zwitterionic amino acids (in which the most basic site is protonated). (C) 2003 Elsevier Science B.V. All rights reserved.
引用
收藏
页码:509 / 524
页数:16
相关论文
共 58 条
[1]  
Aidley DJ., 1996, ION CHANNELS MOL ACT
[2]  
[Anonymous], 2001, ADV ORGANIC CHEM REA
[3]   An absolute sodium cation affinity scale: Threshold collision-induced dissociation experiments and ab initio theory [J].
Armentrout, PB ;
Rodgers, MT .
JOURNAL OF PHYSICAL CHEMISTRY A, 2000, 104 (11) :2238-2247
[4]   THE BINDING-ENERGIES OF CU+-(H2O)N AND CU+-(NH3)N (N = 1-4) [J].
BAUSCHLICHER, CW ;
LANGHOFF, SR ;
PARTRIDGE, H .
JOURNAL OF CHEMICAL PHYSICS, 1991, 94 (03) :2068-2072
[5]   ON THE SODIUM AND LITHIUM ION AFFINITIES OF SOME ALPHA-AMINO-ACIDS [J].
BOJESEN, G ;
BREINDAHL, T ;
ANDERSEN, UN .
ORGANIC MASS SPECTROMETRY, 1993, 28 (12) :1448-1452
[7]   PROTON AND SODIUM-ION AFFINITIES OF GLYCINE AND ITS SODIUM-SALT IN THE GAS-PHASE - ABINITIO CALCULATIONS [J].
BOUCHONNET, S ;
HOPPILLIARD, Y .
ORGANIC MASS SPECTROMETRY, 1992, 27 (02) :71-76
[8]   Zwitterionic vs. charge-solvated structures in the binding of arginine to alkali metal ions in the gas phase [J].
Cerda, BA ;
Wesdemiotis, C .
ANALYST, 2000, 125 (04) :657-660
[9]   Thermochemistry and structures of Na+ coordinated mono- and disaccharide stereoisomers [J].
Cerda, BA ;
Wesdemiotis, C .
INTERNATIONAL JOURNAL OF MASS SPECTROMETRY, 1999, 189 (2-3) :189-204
[10]   Li+, Na+, and K+ binding to the DNA and RNA nucleobases. Bond energies and attachment sites from the dissociation of metal ion-bound heterodimers [J].
Cerda, BA ;
Wesdemiotis, C .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1996, 118 (47) :11884-11892