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Diastereomeric differentiation of norbornene amino acid peptides by electrospray ionization tandem mass spectrometry.
Rapid Commun Mass Spectrom. 2009 Sep; 23(18):2965-74.RC

Abstract

A new class of diastereomeric pairs of non-natural amino acid peptides derived from butyloxycarbonyl (Boc-)protected cis-(2S,3R)- and trans-(2S,3S)-beta-norbornene amino acids including a monomeric pair have been investigated by electrospray ionization (ESI) tandem mass spectrometry using quadrupole time-of-flight (Q-TOF) and ion-trap mass spectrometers. The protonated cis-BocN-beta-nbaa (2S,3R) (1) (betanbaa = beta-norbornene amino acid) eliminates the Boc group to form [M+H-Boc+H](+), whereas an additional ion [M+H-C(4)H(8)](+) is formed from trans-BocN-beta-nbaa (2S,3S) (2). Similarly, it is observed that the peptide diastereomers (di-, tri- and tetra-), with cis-BocN-beta-nbaa (2S,3R)- at the N-terminus, initially eliminate the Boc group to form [M+H-Boc+H](+) which undergo further fragmentation to give a set of product ions that are different for the peptides with trans-BocN-beta-nbaa (2S,3S)- at the N-terminus. Thus the Boc group fragments differently depending on the configuration of the amino acid present at the N-terminus. It is also observed that the peptide bond cleavage in these peptides is less favoured and most of the product ions are formed due to retro-Diels-Alder fragmentation. Interestingly, sodium-cationized peptide diastereomers mainly yield a series of retro-Diels-Alder fragment ions which are different for each diastereomer as they are formed starting from [M+Na-Boc+H](+) in peptides with cis-BocN-beta-nbaa (2S,3R)- at the N-terminus, and [M+Na-C(4)H(8)](+) in peptides with trans-BocN-beta-nbaa (2S,3S)- at the N-terminus. All these results clearly indicate that these diastereomeric pairs of peptides yield characteristic product ions which help distinguish the isomers.

Authors+Show Affiliations

National Centre for Mass Spectrometry, Indian Institute of Chemical Technology, Hyderabad 500 007, India.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Evaluation Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19681066

Citation

Raju, B, et al. "Diastereomeric Differentiation of Norbornene Amino Acid Peptides By Electrospray Ionization Tandem Mass Spectrometry." Rapid Communications in Mass Spectrometry : RCM, vol. 23, no. 18, 2009, pp. 2965-74.
Raju B, Ramesh V, Sudhakar A, et al. Diastereomeric differentiation of norbornene amino acid peptides by electrospray ionization tandem mass spectrometry. Rapid Commun Mass Spectrom. 2009;23(18):2965-74.
Raju, B., Ramesh, V., Sudhakar, A., Ramesh, M., Sarma, V. U., Chandrasekhar, S., & Srinivas, R. (2009). Diastereomeric differentiation of norbornene amino acid peptides by electrospray ionization tandem mass spectrometry. Rapid Communications in Mass Spectrometry : RCM, 23(18), 2965-74. https://doi.org/10.1002/rcm.4211
Raju B, et al. Diastereomeric Differentiation of Norbornene Amino Acid Peptides By Electrospray Ionization Tandem Mass Spectrometry. Rapid Commun Mass Spectrom. 2009;23(18):2965-74. PubMed PMID: 19681066.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Diastereomeric differentiation of norbornene amino acid peptides by electrospray ionization tandem mass spectrometry. AU - Raju,B, AU - Ramesh,V, AU - Sudhakar,A, AU - Ramesh,M, AU - Sarma,V U M, AU - Chandrasekhar,S, AU - Srinivas,R, PY - 2009/8/15/entrez PY - 2009/8/15/pubmed PY - 2009/10/21/medline SP - 2965 EP - 74 JF - Rapid communications in mass spectrometry : RCM JO - Rapid Commun Mass Spectrom VL - 23 IS - 18 N2 - A new class of diastereomeric pairs of non-natural amino acid peptides derived from butyloxycarbonyl (Boc-)protected cis-(2S,3R)- and trans-(2S,3S)-beta-norbornene amino acids including a monomeric pair have been investigated by electrospray ionization (ESI) tandem mass spectrometry using quadrupole time-of-flight (Q-TOF) and ion-trap mass spectrometers. The protonated cis-BocN-beta-nbaa (2S,3R) (1) (betanbaa = beta-norbornene amino acid) eliminates the Boc group to form [M+H-Boc+H](+), whereas an additional ion [M+H-C(4)H(8)](+) is formed from trans-BocN-beta-nbaa (2S,3S) (2). Similarly, it is observed that the peptide diastereomers (di-, tri- and tetra-), with cis-BocN-beta-nbaa (2S,3R)- at the N-terminus, initially eliminate the Boc group to form [M+H-Boc+H](+) which undergo further fragmentation to give a set of product ions that are different for the peptides with trans-BocN-beta-nbaa (2S,3S)- at the N-terminus. Thus the Boc group fragments differently depending on the configuration of the amino acid present at the N-terminus. It is also observed that the peptide bond cleavage in these peptides is less favoured and most of the product ions are formed due to retro-Diels-Alder fragmentation. Interestingly, sodium-cationized peptide diastereomers mainly yield a series of retro-Diels-Alder fragment ions which are different for each diastereomer as they are formed starting from [M+Na-Boc+H](+) in peptides with cis-BocN-beta-nbaa (2S,3R)- at the N-terminus, and [M+Na-C(4)H(8)](+) in peptides with trans-BocN-beta-nbaa (2S,3S)- at the N-terminus. All these results clearly indicate that these diastereomeric pairs of peptides yield characteristic product ions which help distinguish the isomers. SN - 1097-0231 UR - https://www.unboundmedicine.com/medline/citation/19681066/Diastereomeric_differentiation_of_norbornene_amino_acid_peptides_by_electrospray_ionization_tandem_mass_spectrometry_ L2 - https://doi.org/10.1002/rcm.4211 DB - PRIME DP - Unbound Medicine ER -