Gas-phase Complexation and Dissociation of Amino Acids with Metal Ions

• Main Author: 蘇獻昌
• Other Authors: 劉建忠
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/40879361297931287472

碩士 === 東海大學 === 化學系 === 92 === Abstract Tandem mass spectrometric techquine was applied for study of gas-phase proton affinities of amino acids and investigated the complexation of amino acids with metal ions. From our experiment results, the binding abilities of amino acids with a variety of metal ions are determined by the metal ion’s radius, charge density, electrostatic force or electronic configuration. Li+ and Na+ bind tightly with amino acids. After collisional activation, the amino acid/metal ion complexes will dissociate to form free metal ions and other fragment ions in a collision activated dissociation (CAD) spectrum. As the size of the metal ions increased (such as K+, Rb+, and Cs+), the bonding strength between amino acid and metal ion is weakened because of increasing steric factor and decreasing charge density. Dissociation of this complex is relatively simple. Only metal ion is found and no other fragmentation occurs. Complex of alkaline-earth metal ion, having stronger electrostatic attraction than the alkali metal ion, shows different fragmentation pathways which breaking the structure of amino acid. Transition metals have different complexation properties with amino acids because of the differences in their electronic configurations. Moreover, electron configuration of copper is [Ar]3d104s1. It can lose an e- to form a stable ion complex with amino acid.