- 作者: 何永皓, 陳錦紋, 胡采琳
- 作者服務機構: Department of Applied Chemistry, National University of Kaohsiung, Kaohsiung 811, Taiwan, R.O.C.
- 中文摘要: Native non-covalently bonded protein-protein and protein-substrate complexes are of great interest and have been extensively studied by electrospray ionization mass spectrometry (ESI-MS). Multiply charged protein homomultimeric complexes are shown to form by ESI-MS. This study addresses factors that can artificially induce the formation of multiply charged protein homomultimeric complexes. Cytochrome c (Cyt c) and ubiquitin, which are monomers in solution, were found to generate (Cyt c)mn+ by electrospray ionization (ESI). The homomultimeric complexes were not limited to dimeric complexes but include also multiply charged trimers, tetramers, and pentamers. The observation of these homomultimeric complexes has never been revealed from a Cyt c solution at the concentration as low as 10 μM. Increasing the concentration of Cyt c enhanced the formation of (Cyt c)mn+ as expected; however, the protein concentration does not affect the relative intensities of monomeric and dimeric complexes. Additionally, the enrichment of NH4OH also promotes the formation of (Cyt c)mn+. Notably, source collision-induced dissociations (source-CID) of (Cyt c)mn+ alter the charge state distribution (CSD) and may lead to an incorrect interpretation of Cyt c conformations. Hence, extra care should be taken when using CSD to interpret the conformation of a protein derived from ESI-MS.
- 英文摘要: --
- 中文關鍵字: Cytochrome c; Homomultimeric complexes; Asymmetric charge portioning; Mass spectrometry; Collision induced dissociation; Electrospray ionization; Charge state distribution.
- 英文關鍵字: --