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Electrospray tandem mass spectrometry of alkali-cationized BocN-carbo-alpha,beta- and -beta,alpha-peptides: Differentiation of positional isomers.
Rapid Commun Mass Spectrom. 2006; 20(22):3351-60.RC

Abstract

Dissociation pathways of a series of alkali-cationized hybrid peptides, viz., Boc-alpha,beta- and -beta,alpha-carbopeptides, synthesized from C-linked carbo-beta3-amino acids [Caa (S)] and alpha-alanine (L-Ala), have been investigated by electrospray ionization tandem mass spectrometry. The positional isomers (six pairs) of the cationized alpha,beta- and beta,alpha-peptides can be differentiated by the collision-induced dissociation (CID) spectra of their [M + Cat-Boc + H]+ ions which give characteristic series of alkali-cationized C- (x(n)+, y(n)+, z(n)+) and N-terminal (a(n)+, b(n)+, c(n)+) ions. Another noteworthy difference is cationized beta,alpha-peptides eliminate a molecule of ammonia whereas this pathway is absent for alpha,beta-peptides. This is useful for identifying the presence of a beta-amino acid at the N-terminus. The CID spectra of [M + Cat-Boc + H]+ ions of these peptide acids show abundant rearrangement [b(n) + 17 + Cat]+ (n = 1 to n-1) ions which is diagnostic for distinguishing between alpha- and beta-amino acid at the C-terminus. MS(n) experiments of [b(n) + Li-H]+ ions from these hybrid peptides showed the loss of CO and 72 u giving rise to [a(n) + Li-H]+ and cationized nitrile product ions which render support to earlier proposals that b(n)+ or [b(n) + Cat-H]+ ions have protonated or cationized oxazolinone structures, respectively.

Authors+Show Affiliations

National Center 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 available

Pub Type(s)

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

Language

eng

PubMed ID

17051608

Citation

Reddy, P Nagi, et al. "Electrospray Tandem Mass Spectrometry of Alkali-cationized BocN-carbo-alpha,beta- and -beta,alpha-peptides: Differentiation of Positional Isomers." Rapid Communications in Mass Spectrometry : RCM, vol. 20, no. 22, 2006, pp. 3351-60.
Reddy PN, Srikanth R, Srinivas R, et al. Electrospray tandem mass spectrometry of alkali-cationized BocN-carbo-alpha,beta- and -beta,alpha-peptides: Differentiation of positional isomers. Rapid Commun Mass Spectrom. 2006;20(22):3351-60.
Reddy, P. N., Srikanth, R., Srinivas, R., Sharma, V. U., Sharma, G. V., & Nagendar, P. (2006). Electrospray tandem mass spectrometry of alkali-cationized BocN-carbo-alpha,beta- and -beta,alpha-peptides: Differentiation of positional isomers. Rapid Communications in Mass Spectrometry : RCM, 20(22), 3351-60.
Reddy PN, et al. Electrospray Tandem Mass Spectrometry of Alkali-cationized BocN-carbo-alpha,beta- and -beta,alpha-peptides: Differentiation of Positional Isomers. Rapid Commun Mass Spectrom. 2006;20(22):3351-60. PubMed PMID: 17051608.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Electrospray tandem mass spectrometry of alkali-cationized BocN-carbo-alpha,beta- and -beta,alpha-peptides: Differentiation of positional isomers. AU - Reddy,P Nagi, AU - Srikanth,R, AU - Srinivas,R, AU - Sharma,V U M, AU - Sharma,G V M, AU - Nagendar,P, PY - 2006/10/20/pubmed PY - 2007/1/20/medline PY - 2006/10/20/entrez SP - 3351 EP - 60 JF - Rapid communications in mass spectrometry : RCM JO - Rapid Commun Mass Spectrom VL - 20 IS - 22 N2 - Dissociation pathways of a series of alkali-cationized hybrid peptides, viz., Boc-alpha,beta- and -beta,alpha-carbopeptides, synthesized from C-linked carbo-beta3-amino acids [Caa (S)] and alpha-alanine (L-Ala), have been investigated by electrospray ionization tandem mass spectrometry. The positional isomers (six pairs) of the cationized alpha,beta- and beta,alpha-peptides can be differentiated by the collision-induced dissociation (CID) spectra of their [M + Cat-Boc + H]+ ions which give characteristic series of alkali-cationized C- (x(n)+, y(n)+, z(n)+) and N-terminal (a(n)+, b(n)+, c(n)+) ions. Another noteworthy difference is cationized beta,alpha-peptides eliminate a molecule of ammonia whereas this pathway is absent for alpha,beta-peptides. This is useful for identifying the presence of a beta-amino acid at the N-terminus. The CID spectra of [M + Cat-Boc + H]+ ions of these peptide acids show abundant rearrangement [b(n) + 17 + Cat]+ (n = 1 to n-1) ions which is diagnostic for distinguishing between alpha- and beta-amino acid at the C-terminus. MS(n) experiments of [b(n) + Li-H]+ ions from these hybrid peptides showed the loss of CO and 72 u giving rise to [a(n) + Li-H]+ and cationized nitrile product ions which render support to earlier proposals that b(n)+ or [b(n) + Cat-H]+ ions have protonated or cationized oxazolinone structures, respectively. SN - 0951-4198 UR - https://www.unboundmedicine.com/medline/citation/17051608/Electrospray_tandem_mass_spectrometry_of_alkali_cationized_BocN_carbo_alphabeta__and__betaalpha_peptides:_Differentiation_of_positional_isomers_ L2 - https://doi.org/10.1002/rcm.2751 DB - PRIME DP - Unbound Medicine ER -