摘?要 本實驗主要是利用三段式四極矩質譜儀，研究在氣態下胺基酸與質子及金屬離子所形成錯合離子之相對親和力及結構特性之探討。 錯合離子的鍵結及斷裂性質與金屬離子的半徑、電荷密度、靜電引力或電子組態有關；半徑較小的鋰、鈉離子與大部分胺基酸較能緊密結合，所以此金屬錯合物的碰撞活化解離圖譜除了丟失金屬離子外，也有分子的碎裂離子。相對於半徑較大的金屬離子，如銣、銫等，其與胺基酸所形成的錯合離子，由於空間效應使分子與金屬間的鍵結能力較弱，經碰撞活化解離後，這些錯合離子的裂解形式，只進行簡單的去錯合反應（decomplexation reaction），不會引起任何的骨幹斷裂。正二價的鹼土金屬，雖與正一價的電子組態相同，但二價離子的靜電引力大於一價離子，鍵結能力較強，所以鹼土金屬的碰撞活化解離，包含了胺基酸的結構斷裂。過渡金屬如：鐵、鈷、鎳、銅及銀等，由於電子組態不同，因此與胺基酸分子會形成不同價數的錯合離子。鐵、鈷、鎳均以正二價的形式與胺基酸分子形成錯合離子，而銅的電子組態為[Ar]3d104s1，容易失去一個電子形成[Ar]3d104s0，所得之圖譜性質有別於其他過渡金屬與胺基酸之結合形式。 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.
