✍ Scribed by Roman A. Zubarev
No coin nor oath required. For personal study only.
| I. | Introduction | 58 |
| | A. Challenges in the Gas‐Phase Fragmentation of Polypeptides | 58 |
| | B. Ion–Electron Interactions | 58 |
| | C. Nomenclature | 59 |
| II. | Instrumental Realization and Applications | 60 |
| III. | Electron‐Capture Dissociation | 61 |
| | A. Electron Capture | 61 |
| | B. NC~α~ Bond Cleavage | 62 |
| | C. SS Bond Reduction | 64 |
| | D. Dissociation of Strong Bonds in the Presence of Weak Bonding | 65 |
| | E. Frequencies of NC~α~ Bond Cleavage | 67 |
| IV. | Electronic Excitation | 68 |
| | A. Hot‐Electron‐Capture Dissociation (HECD) | 68 |
| | B. Electronic Excitation Dissociation (EED) | 69 |
| V. | Vibrational Excitation | 70 |
| | A. Vibrational Excitation of Even‐Electron Species | 70 |
| | B. Vibrational Excitation of Radical Species | 71 |
| VI. | Electron Detachment | 72 |
| | A. Ionization | 72 |
| | B. Electron‐Detachment Dissociation (EDD) | 73 |
| VII. | Conclusions | 74 |
| References | | 74 |
Reactions of electrons in the energy range below 70 eV with polypeptide cations and anions are reviewed, as well as their applications for the structural analysis of polypeptides. At very low energies (≤ 0.1 eV), the major outcome is electron‐capture dissociation (ECD) of SS and backbone NC~α~ bonds, leading to c′ and z· fragments. ECD is useful in sequencing and characterization of post‐translational modifications (PTMs), because c′, z· fragmentation is abundant and the fragments usually retain labile groups. Electron capture at higher energies (3–13 eV) induces secondary fragmentation in radical z· fragments; this hot ECD (HECD) allows one to distinguish between the isomeric leucine and isoleucine residues. If a hot electron is not captured, then the induced electronic excitation converts internally into vibrational energy, resulting in fragmentation of the C(O)N backbone bond (so‐called EIEIO process). Above 9–10 eV, further ionization of n‐charged cations occurs. If the formed (n + 1)+· cations capture electrons, then the C~α~C backbone bond is usually broken. For anions that collide with ≈20 eV electrons, the ejection of an electron leads to the creation of a radical positive charge (hole) that recombines internally with a negative charge. Such recombination leads to various backbone bond cleavages. This electron‐detachment dissociation (EDD) is analogous to ECD for negative ions. © 2003 Wiley Periodicals, Inc., Mass Spec Rev 22:57–77, 2003; Published online in Wiley InterScience (www.interscience.wiley.com)
📜 SIMILAR VOLUMES
The reactions of o-, m-and p-benzyne anions and the phenide ion with a series of neutral reagents are described. The m-and p-benzyne anions display similar behavior towards acids, NO and , analogous to that of phenide ion but clearly di †erent from that of o-benzyne anion. The strongly basic and nu
## OMS Letters Dear Sir, ## Gas-phase Reactions of the Sulphur Distonic Ion (CH,),SCH,' with Alkenes Distonic ions are well recognized as key intermediates in the unimolecular reactions of radical cations in the gas phase'-, and the bimolecular chemistry of these species has been described in a