傅立葉質譜儀應用於血紅素蛋白的研究

Studies of Gaseous Myoglobin Ions by Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry

10.6623/chem.2004028

魏世嘉(Shih-Chia Wei)；王亦生(Yi-Sheng Wang)；韓肇中(Chau-Chung Han)；張煥正(Huan-Cheng Chang)

傅立葉質譜儀 ； 肌紅蛋白 ； 原血紅素 ； 電噴灑游離法 ； Fourier-transform ion cyclotron resonance mass spectrometry ； myoglobin ； heme ； electrospray ionization

化學

62卷3期（2004 / 09 / 01）

355 - 363

繁體中文

近年來，由於電噴灑游離法(Electrospray-ionization，簡寫為ESI)以及基質輔助雷射脫附/游離法(Matrix-assisted laser desorption Ionization，簡寫為MALDI)的發明，促使蛋白質體學的蓬勃發展。其中電噴灑游離法具有(1)低破壞性：可避免游離的過程中複雜化學反應的產生；(2)連續性：適合作為HPLC與質譜儀連結的介面等兩點特性，故常被用來產生氣相中的低揮發性複雜分子，進而研究理化特性。肌紅蛋白(Myoglobin)為包覆單一分子原血紅素(heme)的蛋白質，是人體內進行氧化還原時重要的蛋白質之一。由於結構簡單與分子量大小適中，故被廣泛當作血紅素蛋白的原型作研究。在此我們選擇經電噴灑游離法產生的離子，探討：(1)當溶液pH值改變時引發氣相蛋白質離子結構特性的改變；(2)並利用傅立葉質譜儀(Fourier Transform-Ion Cyclotron Resonance,簡稱FT-ICR)量測肌紅蛋白肽鏈與原血紅素鍵結的強度；(3)比較不同電荷的原血紅素與肌紅蛋白肽鏈鍵結的強弱。

Myoglobin is one of the heme proteins responsible for oxygen transfer in most living systems. Holomyoglobin is the native form of myoglobin, which possesses a heme group bound to the protein's polypeptide chain by noncovalent interactions, forming a complex. The heme is prone to detachment induced by either acid or methanol in solution. The physiological properties of myoglobin in condensed phases have been extensively investigated in the past five decades. With the development of electrospray ionization (ESI) as an ion source, it is now possible to study the nature of the noncovalent interactions between heme and the polypeptide chain in the gas phase without interference from solvent molecules. Using a 7 telsa Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer, we have studied gaseous myoglobin ions from a chemical kinetics perspective. We have examined the conformational change of myoglobin ions as a function of solution pH and determined the dissociation energy of the protein complex to be 1.09 ± 0.17eV.