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Talaty ER, Young SM, Dain RP, Van Stipdonk MJ. A study of fragmentation of protonated amides of some acylated amino acids by tandem mass spectrometry: observation of an unusual nitrilium ion. Rapid Commun Mass Spectrom 2011; 25:1119-1129. [PMID: 21488111 DOI: 10.1002/rcm.4965] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A tandem mass spectrometric study of a series of secondary amides of acetylglycine and hippuric acid utilizing electrospray ionization (ESI) was conducted. Among the fragment ions observed was an unusual one, which we have determined to be a nitrilium ion having the structure CH3-C≡N⊕-Ph or Ph-C≡N⊕-Ph by loss of the full mass of glycine as a neutral fragment. A mechanism that we propose involves an initial protonation of the oxygen atom at the N-terminus, followed by cyclization to a five-membered imidazolium ring, and its subsequent collapse to the nitrilium ion. This mechanism is supported by extensive isotopic labels and considerable variation of substituents. A similar study of the amides of acyl β-alanine and acyl γ-aminobutyric acid revealed that the former furnishes the same nitrilium ion, but not the latter. Thus, a six-membered intermediate is also possible and capable of losing the full mass of β-alanine as a neutral fragment. When the size of the ring is forced to be seven-membered, this pathway is blocked. When this study was expanded to include a variety of N-acylproline amides, the nitrilium ion was observed in 100% abundance only when the acyl group was acetyl. Thus a proline effect (involvement of a strained bicyclic [3.3.0] structure) is being observed.
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Affiliation(s)
- Erach R Talaty
- Department of Chemistry, Wichita State University, Wichita, KS 67260-0051, USA.
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Dou D, Talaty ER, Moore CE, Bullinger JC, Eichhorn DM, Groutas WC. Formation of an unusual product in the reaction of a 1,2,5-thiadiazolidine 1,1-dioxide-derived thioether with sulfuryl chloride. J Heterocycl Chem 2009. [DOI: 10.1002/jhet.136] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
Variable-temperature inversion transfer NMR is used to determine the kinetic and thermodynamic parameters of cis-trans isomerization of N-Ac-(3R) and (3S)-fluoroproline-OMe.
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Affiliation(s)
- Colin A Thomas
- Department of Chemistry, Wichita State University, Wichita, KS 67260-0051, USA
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Osburn SM, Ochola SO, Talaty ER, Van Stipdonk MJ. Formation of [b3 - 1 + cat]+ ions from metal-cationized tetrapeptides containing beta-alanine, gamma-aminobutyric acid or epsilon-aminocaproic acid residues. J Mass Spectrom 2008; 43:1458-1469. [PMID: 18449851 DOI: 10.1002/jms.1418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The presence and position of a single beta-alanine (betaA), gamma-aminobutyric acid (gammaABu) or epsilon-aminocaproic acid (Cap) residue has been shown to have a significant influence on the formation of b(n)+ and y(n)+ product ions from a series of model, protonated peptides. In this study, we examined the effect of the same residues on the formation of analogous [b3 - 1 + cat]+ products from metal (Li+, Na+ and Ag+)-cationized peptides. The larger amino acids suppress formation of b3+ from protonated peptides with general sequence AAXG (where X = beta-alanine, gamma-aminobutyric acid or epsilon-aminocaproic acid), presumably because of the prohibitive effect of larger cyclic intermediates in the 'oxazolone' pathway. However, abundant [b3 - 1 + cat]+ products are generated from metal-cationized versions of AAXG. Using a group of deuterium-labeled and exchanged peptides, we found that formation of [b3 - 1 + cat]+ involves transfer of either amide or alpha-carbon position H atoms, and the tendency to transfer the atom from the alpha-carbon position increases with the size of the amino acid in position X. To account for the transfer of the H atom, a mechanism involving formation of a ketene product as [b3 - 1 + cat]+ is proposed.
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Affiliation(s)
- Sandra M Osburn
- Department of Chemistry, Wichita State University, 1845 Fairmount, Wichita, KS 67260-0051, USA
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Talaty ER, Chueachavalit C, Osburn S, Van Stipdonk MJ. Investigation of the neutral loss of a full amino acid mass during collision-induced dissociation of the b(3)+ ion derived from a model peptide containing a 4-aminobutyric acid residue. Rapid Commun Mass Spectrom 2007; 21:2529-37. [PMID: 17610213 DOI: 10.1002/rcm.3120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
In a previous study we found that a dominant fragmentation pathway observed for collision-induced dissociation (CID) of b(3)+ derived from peptides with sequence AXAG, where X is gamma-aminobutyric acid (gammaAbu) or epsilon-aminocaproic acid (Cap), involved the loss of 89 mass units (u). A neutral loss of 89 u corresponded to the free acid mass of an alanine (A) residue. This specific pathway was studied in greater detail here using a series of A(gammaAbu)AG peptides with strategic positioning of (15)N, (13)C and (2)H isotope labels. Based on the extensive labeling, several possible routes to the net elimination of 89 u are proposed. One is based on initial elimination of either aziridinone or imine and CO, followed by opening of an oxazolinone, tautomerization and elimination of H2O. Another involves formation of an aziridinone by cleavage of the N-terminal amide bond, and transfer of O and H atoms to this fragment via an H-bonded ion-molecule complex to complete the loss of 89 u. Both types of pathway include the transfer/migration of H atoms from the alpha-carbon position of gammaAbu or A residues.
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Affiliation(s)
- Erach R Talaty
- Department of Chemistry, Wichita State University, Wichita, KS 67260-0051,
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Talaty ER, Clague AR, Behrens JM, Agho MO, Burger DH, Hendrixson TL, Korst KM, Khanh TT, Kell RA, Dibaji N. Reaction of Aziridinones with 2-Lithio-1, 3-Dithiane: Selective Cleavage of the Aziridinone Ring. SYNTHETIC COMMUN 2006. [DOI: 10.1080/00397918108061877] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Talaty ER, Cooper TJ, Osburn S, Van Stipdonk MJ. Collision-induced dissociation of protonated tetrapeptides containing beta-alanine, gamma-aminobutyric acid, epsilon-aminocaproic acid or 4-aminomethylbenzoic acid residues. Rapid Commun Mass Spectrom 2006; 20:3443-55. [PMID: 17066369 DOI: 10.1002/rcm.2754] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The influence of the presence and position of a single beta-alanine, gamma-aminobutyric acid, epsilon-aminocaproic acid or 4-aminomethylbenzoic acid residue on the tendency to form b(n)+ -and y(n)+ -type product ions was determined using a group of protonated tetrapeptides with general sequence XAAG, AXAG and AAXG (where X refers to the position of amino acid substitution). The hypothesis tested was that the 'alternative' amino acids would influence product ion signal intensities by inhibiting or suppressing either the nucleophilic attack or key proton transfer steps by forcing the adoption of large cyclic intermediates or blocking cyclization altogether. We found that specific b ions are diminished or eliminated completely when betaA, gammaAbu, Cap or 4AMBz residues are positioned such that they should interfere with the intramolecular nucleophilic attack step. In addition, differences in the relative proton affinities of the alternative amino acids influence the competition between complementary b(n) and y(n) ions. For both the AXAG and the XAAG series of peptides, collision-induced dissociation (CID) generated prominent b ions despite potential inhibition or suppression of intramolecular proton migration by the betaA, gammaAbu, Cap or 4AMBz residues. The prominent appearance of b ions from the AXAG and XAAG peptide is noteworthy, and suggests either that proton migration occurs through larger, 'whole' peptide cyclic intermediates or that fragmentation proceeds through a population of [M+H]+ isomers that are initially protonated at amide O atoms.
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Affiliation(s)
- Erach R Talaty
- Department of Chemistry, Wichita State University, Wichita, KS 67260-0051, USA
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Talaty ER, Cooper TJ, Piland DL, Bateman DJ, Syed A, Stevenson W, Van Stipdonk MJ. A study of the elimination of water from lithium-cationized tripeptide methyl esters by means of tandem mass spectrometry and isotope labeling. Rapid Commun Mass Spectrom 2006; 20:3007-17. [PMID: 16969769 DOI: 10.1002/rcm.2694] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Extensive isotope labeling (2H, 13C and 15N), collision-induced dissociation (CID) and multiple-stage tandem mass spectrometry were used to investigate the elimination of H2O from a series of model, metal-cationized tripeptide methyl esters. The present results corroborate our earlier suggestion that loss of water from lithiated peptides is initiated by a nucleophilic attack from the N-terminal side upon an amide carbonyl carbon atom to form a five-membered ring as an intermediate followed by 1,2-elimination of water. We show that the nucleophilic atom is the oxygen atom of the N-terminal amide group in the fragmentation of [AcGGGOMe+Li]+ as well as [GGGOMe+Li]+. However, the subsequent fragmentation is markedly different in the two cases as a result of the absence and presence of a free amino group. In particular, extensive scrambling of protons in the alpha-positions of GGGOMe is observed, presumably as a consequence of intervention of the basic amino group.
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Affiliation(s)
- Erach R Talaty
- Department of Chemistry, Wichita State University, Wichita, KS 67260-0051, USA.
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Cooper TJ, Talaty ER, Van Stipdonk MJ. Novel fragmentation pathway for CID of (b(n) - 1 + Cat)+ ions from model, metal cationized peptides. J Am Soc Mass Spectrom 2005; 16:1305-10. [PMID: 15990332 DOI: 10.1016/j.jasms.2005.01.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2004] [Revised: 12/26/2004] [Accepted: 01/05/2005] [Indexed: 05/03/2023]
Abstract
We report a new fragmentation pathway for the CID of (b3 - 1 + Cat)+ product ions derived from the model peptide AXAG, where X = beta-alanine, gamma-aminobutyric acid, epsilon-amino-n-caproic acid, or 4-aminomethylbenzoic acid. By changing the amino acid to the C-terminal side of the amino acid X, and incorporating 15N and 13C labeled residues at the same position, we conclude that the dissociation pathway most likely leads to a metal cationized nitrile. With respect to the various amino acids at position X, the putative nitrile product becomes more prominent, relative to the conventional (a3 - 1 + Cat)+ species, in the order beta-alanine < gamma-aminobutyric acid < epsilon-aminocaproic acid < 4-aminomethylbenzoic acid. The pathway is not observed for peptides with alpha-amino acids at position X. The product ion is observed most prominently during the CID of Li+ and Na+ cationized peptides, only to a small extent for Ag+ cationized peptides, and not at all from protonated analogues.
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Affiliation(s)
- Travis J Cooper
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, USA
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Talaty ER, Raja S, Storhaug VJ, Dölle A, Carper WR. Raman and Infrared Spectra and ab Initio Calculations of C2-4MIM Imidazolium Hexafluorophosphate Ionic Liquids. J Phys Chem B 2004. [DOI: 10.1021/jp040199s] [Citation(s) in RCA: 381] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Erach R. Talaty
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, and Institut für Physikalische Chemie, Rheinisch-Westfälische Technische Hochschule Aachen, 52056 Aachen, Germany
| | - Sidhartha Raja
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, and Institut für Physikalische Chemie, Rheinisch-Westfälische Technische Hochschule Aachen, 52056 Aachen, Germany
| | - Vincent J. Storhaug
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, and Institut für Physikalische Chemie, Rheinisch-Westfälische Technische Hochschule Aachen, 52056 Aachen, Germany
| | - Andreas Dölle
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, and Institut für Physikalische Chemie, Rheinisch-Westfälische Technische Hochschule Aachen, 52056 Aachen, Germany
| | - W. Robert Carper
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, and Institut für Physikalische Chemie, Rheinisch-Westfälische Technische Hochschule Aachen, 52056 Aachen, Germany
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Anbalagan V, Silva ATM, Rajagopalachary S, Bulleigh K, Talaty ER, Van Stipdonk MJ. Influence of "alternative" C-terminal amino acids on the formation of [b3 + 17 + Cat]+ products from metal cationized synthetic tetrapeptides. J Mass Spectrom 2004; 39:495-504. [PMID: 15170745 DOI: 10.1002/jms.610] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The aim of this study was to investigate the dissociation patterns, and in particular the relative abundance of [b(3) + 17 + Cat](+), for peptides with C-termini designed to allow transfer of the -OH required to generate the product ion, but not necessarily as the most favored pathway. Working with the hypothesis that formation of a five-membered ring intermediate, including intramolecular nucleophilic attack by a carbonyl oxygen atom, is an important mechanistic step, several model peptides with general sequence AcFGGX were synthesized, metal cationized by electrospray ionization and subjected to collision-induced dissociation (CID). The amino acid at position X was one that either required a larger ring intermediate (beta-alanine, gamma-aminobutyric acid and epsilon-amino-n-caproic acid to generate six-, seven- or nine- membered rings, respectively) to transfer -OH, lacked a structural element required for nucleophilic attack (aminoethanol) or prohibited cyclization because of the inclusion of a rigid ring (p- and m-aminobenzoic acid). For Ag(+), Li(+) and Na(+) cationized peptides, our results show that amino acids requiring the adoption of larger ring intermediates suppressed the formation of [b(3) + 17 + Cat](+), while amino acids that prohibit cyclization eliminated the reaction pathway completely. Formation of [b(3) - 1 + Cat](+) from the alkali metal cationized versions was not a favorable process upon suppression or elimination of the [b(3) + 17 + Cat](+) pathway: the loss of H(2)O to form [M - H(2)O + Cat](+) was instead the dominant dissociation reaction observed. Multiple-stage dissociation experiments suggest that [M - H(2)O + Cat](+) is not [b(4) - 1 + Cat](+) arising from the loss of H(2)O from the C-terminus, but may instead be a species that forms via a mechanism involving the elimination of an oxygen atom from an amide group.
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Affiliation(s)
- V Anbalagan
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, USA
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Anbalagan V, Perera BA, Silva ATM, Gallardo AL, Barber M, Barr JM, Terkarli SM, Talaty ER, Van Stipdonk MJ. Formation of [b(n) + 17 + Ag]+ product ions from Ag+ cationized native and acetylated peptides. J Mass Spectrom 2002; 37:910-926. [PMID: 12271434 DOI: 10.1002/jms.350] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We compared the tandem mass spectra of a range of native and acetylated Ag(+) cationized peptides to determine the influence of the derivatization step on the abundance of the [b(n) + 17 + Ag](+) product ions. Using tripeptides, the smallest for which the mechanisms to generate [b(2) - 1 + Ag](+) and [b(2) + 17 + Ag](+) products are both operative, we found that in most cases acetylation causes an increase in the abundance of the C-terminal rearrangement ion, [b(2) + 17 + Ag](+), relative to the rival N-terminal rearrangement ion, [b(2) - 1 + Ag](+). The presence of a free amino group to bind to the metal ion significantly influences the relative abundances of the product ions. We propose a mechanism for the formation of the [b(n) + 17 + Ag](+) that is based on the formation of a five-membered oxazolidin-5-one and tetrahedral carbon intermediate that may collapse to a peptide upon release of CO and an imine, aided by the fact that the ring formed during C-terminal rearrangement is both a hemiacylal and hemiaminal. We also identified an influence of amino acid sequence on the relative abundances of the [b(n) + 17 + Ag](+) and [b(n) - 1 + Ag](+) product ions, whereby bulky substituents located on the alpha-carbon of the amino acid to the C-terminal side of the cleavage site apparently promote the formation of the [b(n) + 17 + Ag](+) product over [b(n) - 1 + Ag](+) when the amino acid to the N-terminal side of the cleavage site is glycine. The latter ion is the favored product, however, when the bulky group is positioned on the alpha-carbon of the amino acid to the N-terminal side of the cleavage site.
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Affiliation(s)
- V Anbalagan
- Department of Chemistry, Wichita State University, Wichita, KS 67260-0051, USA
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Russell GA, Moye AJ, Janzen EG, Mak S, Talaty ER. Reaction of resonance stabilized anions. XXVII. Oxidation of carbanions. 2. Oxidation of p-nitrotoluene and derivatives in basic solution. J Org Chem 2002. [DOI: 10.1021/jo01277a035] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Russell GA, Talaty ER, Horrocks RH. Application of electron spin resonance spectroscopy to problems of structure and conformation. IX. Semidiones derived from cyclopentanones. Assignment of structure to steroidal D-ring ketones. J Org Chem 2002. [DOI: 10.1021/jo01288a022] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Talaty ER, Russell GA. Application of Electron Spin Resonance Spectroscopy to Problems of Structure and Conformation. VIII. Semidiones Derived from 9-Methyldecalones and 10-Methyl Steroidal Ketones. Assignment of Structure to A-Ring Steroidal Ketones1. J Org Chem 2002. [DOI: 10.1021/jo01349a001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Russell GA, Talaty ER. Application of Electron Spin Resonance Spectroscopy to Problems of Structure and Conformation. II. Alicyclic Semiquinones Derived from Steroidal Ketones and 2-Decalones. J Am Chem Soc 2002. [DOI: 10.1021/ja01077a069] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Talaty ER, Huang Y, Zandler ME. Are any ten-valence-electron HXY species bent in the ground state? Ab initio optimized energies and shapes of HBO, HBS, HAlO, HAlS, and HCS+ and their isomers. J Am Chem Soc 2002. [DOI: 10.1021/ja00003a008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Russell GA, Tanikaga R, Talaty ER. Application of electron spin resonance spectroscopy to problems of structure and conformation. XXVI. Conversion of .alpha.-hydroxy ketones to 1,2-dithiete, p-dithiin, and 1,2-dithiole radical cations. J Am Chem Soc 2002. [DOI: 10.1021/ja00772a033] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Russell GA, Strom ET, Talaty ER, Weiner SA. Semidiones. I. Acyclic Semidione Radical Anions and Cations Containing a Single Aryl Substituent1. J Am Chem Soc 2002. [DOI: 10.1021/ja00961a027] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Perera BA, Gallardo AL, Barr JM, Tekarli SM, Anbalagan V, Talaty ER, Van Stipdonk MJ. Influence of a ring substituent on the tendency to form H(2)O adducts to Ag(+) complexes with phenylalanine analogues in an ion trap mass spectrometer. J Mass Spectrom 2002; 37:401-413. [PMID: 11948847 DOI: 10.1002/jms.296] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In a previous report we showed that certain binary Ag(+)-amino acid complexes formed adduct ions by the attachment of a single water and methanol molecule when stored in an ion trap mass spectrometer: complexes with aliphatic amino acids and with 4-fluorophenylalanine formed the adduct ions whereas complexes with phenylalanine and tryptophan did not. In this study we compared the tendency of the Ag(+) complexes derived from phenylalanine, 4-fluorophenylalanine, 4-hydroxyphenylalanine (tyrosine), 4-bromophenylalanine, 4-nitrophenylalanine and aminocyclohexanepropionic acid to form water adducts when stored, without further activation, in the ion trap for times ranging from 1 to 500 ms. Because the donation of pi electron density to the Ag(+) ion is a likely determining factor in complex reactivity, our aim in the present study was to determine qualitatively the influence of para-position substituents on the aromatic ring on the formation of the water adducts. Our results show that the reactivity of the complexes is influenced significantly by the presence of the various substituents. Decreases in [M + Ag](+) ion abundance, and increases in adduct ion abundance, both measured as a function of storage time, follow the trend -NO(2) > -Br > -F > -OH > -H. The complex of Ag(+) with 4-nitrophenylalanine was nearly as reactive towards water as the Ag(+) complex with aminocyclohexanepropionic acid, the last being an amino acid devoid of pi character in the ring system. Collision induced dissociation of the [M + Ag](+) species derived from the amino acids produces, among other products, Ag(+) complexes with a para-substituted phenylacetaldehyde: complexes that also form adduct species when stored in the ion trap. The trends in adduct ion formation exhibited by the aldehyde-Ag(+) complex ions were similar to those observed for the precursor complexes of Ag(+) and the amino acids, confirming the influence of the ring substituent.
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Affiliation(s)
- B A Perera
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, USA
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Talaty ER, Van Stipdonk MJ, Hague MJ, Provenzano FA, Boese CA. Determination of regioselectivity in ring opening of tert-butylaziridinones by a combination of (15)N labeling and electrospray ionization-ion trap mass spectrometry. J Mass Spectrom 2002; 37:31-40. [PMID: 11813308 DOI: 10.1002/jms.242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The ring opening of 1,3-di-tert-butylaziridinone by tert-butylamine and aniline was investigated by using electrospray ionization and collision-induced dissociation in an ion trap mass spectrometer in conjunction with (15)N labeling of the two amine nucleophiles. Using the MS(n) capabilities of the ion trap instrument, we were able to monitor the retention of the (15)N label through successive fragmentation steps. Both amines exhibited a remarkable degree of selectivity in that they both cleaved exclusively the 1,3-bond (the alkyl-nitrogen bond). This result is in contrast to that obtained previously with methylamine, which cleaved just the opposite bond, namely, the 1,2-bond (the acyl-nitrogen bond). These contrasting results could not have been predicted by previously published guidelines.
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Affiliation(s)
- E R Talaty
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, USA.
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Talaty ER, Perera BA, Gallardo AL, Barr JM, Van Stipdonk MJ. Elucidation of Fragmentation Pathways for the Collision-Induced Dissociation of the Binary Ag(I) Complex with Phenylalanine. J Phys Chem A 2001. [DOI: 10.1021/jp011411k] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Erach R. Talaty
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051
| | - B. Asiri Perera
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051
| | - Andrea L. Gallardo
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051
| | - Jessica M. Barr
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051
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Perera BA, Ince MP, Talaty ER, Van Stipdonk MJ. Gas phase attachment of water and methanol to Ag(I) complexes with alpha-amino acids in an ion trap mass spectrometer. Rapid Commun Mass Spectrom 2001; 15:615-622. [PMID: 11312512 DOI: 10.1002/rcm.280] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Electrospray ionization was used to generate gas phase complexes of Ag+ with selected alpha-amino acids. Following storage (isolation without collisional activation) in an ion trap mass spectrometer, the mass spectra produced from the complexes of Ag+ with alpha-amino acids such as alanine, valine and tert-leucine contained peaks consistent with the formation of water or methanol molecule adduct ions. The same adduct ions were not present, however, in the mass spectra generated from the Ag+ complexes with phenylalanine, tyrosine and tryptophan following isolation and storage under similar conditions. For those complexes that showed reactivity, the uptake of water and methanol increased with longer storage times in the ion trap. A preliminary molecular modeling study using phenylalanine demonstrated that the aromatic ring coordinates the Ag+ ion, and the interaction between the metal ion and pi-system, in part, is assumed to prohibit the binding of water or methanol during isolation in the gas phase. This conclusion is supported by a comparison of the adduct formation by the Ag+ complexes with phenylalanine, 4-fluorophenylalanine and alpha-aminocyclohexanepropionic acid. In addition, collision induced dissociation experiments involving the Ag+ complexes of phenylalanine, tyrosine and tryptophan suggest that limiting the coordination of the Ag ion by the complexing molecule (i.e. by loss of a coordinating functional group and/or change in structure due to dissociation) results in the binding of a water or methanol molecule during storage in the ion trap. Surprisingly, the bare Ag+ ion, when trapped and stored under identical experimental conditions, formed neither adduct species, suggesting that the attachment of water or methanol may be due to interactions with a molecular orbital within the Ag+/molecule complex.
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Affiliation(s)
- B A Perera
- Department of Chemistry, Wichita State University, Wichita, KS 67260-0051, USA
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Talaty ER, Gomez JA, Dillon JA, Palomino E, Agho MO, Batt BC, Gleason KJ, Park S, Hernandez JR, Yusoff MM, Rupp GA, Malone FC, Brummett MF, Finch CL, Ismail SA, Williams N, Aghakhani M. Reaction of Aziridinones with Thiourea: A Novel Synthesis of Specifically Substituted Glycocyamidines and Hydantoins. SYNTHETIC COMMUN 1987. [DOI: 10.1080/00397918708078787] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Talaty ER, Clague AR, Agho MO, Deshpande MN, Courtney PM, Burger DH, Roberts EF. Reaction of α-lactams with alkynyl-lithium reagents: a novel synthesis of pyrrolinones. ACTA ACUST UNITED AC 1980. [DOI: 10.1039/c39800000889] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
A theoretical study of the
C3v reaction path of the
H- + CH3Cl → CH4+Cl-
SN2 reaction
with the use of the GAUSSIAN 70 program reveals an earlier departure of the
leaving group than in other ab initio studies of similar reactions involving poorer
leaving groups, and predicts an intermediate planar structure that is highly
ionic and which should be represented as a tight ion triplet, H-[CH3+]Cl-.
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Talaty ER, Dupuy AE, Utermoehlen CM, Stekoll LH. Thermal decomposition of α-lactams: a new ring expansion of an α-lactam to a β-lactam system. ACTA ACUST UNITED AC 1973. [DOI: 10.1039/c39730000048] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Wang AHJ, Paul IC, Talaty ER, Dupuy AE. X-Ray crystallographic structure determination of an aziridinone. Demonstration of a non-planar arrangement at nitrogen in an α-lactam. ACTA ACUST UNITED AC 1972. [DOI: 10.1039/c39720000043] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Talaty ER, Russell GA. Application of electron spin resonance spectroscopy to problems of structure and conformation. VII. Radical anions derived from cyclohexanones and decalones. Assignment of structure to 19-nor-3-keto steroids and 18-nor-D-homo-17-keto steroids. J Am Chem Soc 1965; 87:4867-78. [PMID: 4284793 DOI: 10.1021/ja00949a034] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Abstract
Many ketones containing an alpha-methylene group can be converted to alpha-diketone radical anions in dimethyl sulfoxide solution. The resulting radical anions can usually be unambiguously identified by electron spin resonance spectroscopy, and the structure of the starting ketone may be deduced, often without reference to model compounds. The technique is also applicable to alpha-diketones, alpha-bromoketones, and alpha-hydroxyketones.
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