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https://hdl.handle.net/2440/71068
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Type: | Journal article |
Title: | Diagnostic cyclisation reactions which follow phosphate transfer to carboxylate anion centres for energised [M-H]⁻ anions of pTyr-containing peptides |
Other Titles: | Diagnostic cyclisation reactions which follow phosphate transfer to carboxylate anion centres for energised [M-H](-) anions of pTyr-containing peptides |
Author: | Tran, T. Wang, T. Hack, S. Bowie, J. |
Citation: | Rapid Communications in Mass Spectrometry, 2011; 25(17):2489-2499 |
Publisher: | John Wiley & Sons Ltd |
Issue Date: | 2011 |
ISSN: | 0951-4198 1097-0231 |
Statement of Responsibility: | T. T. Nha Tran, Tianfang Wang, Sandra Hack and John H. Bowie |
Abstract: | The low-energy negative ion phosphoTyr to C-terminal -CO(2)PO(3)H(2) rearrangement occurs for energised peptide [M-H](-) anions even when there are seven amino acid residues between the pTyr and C-terminal amino acid residues. The rearranged C-terminal -CO(2)PO(2)H(O(-)) group effects characteristic S(N)i cyclisation/cleavage reactions. The most pronounced of these involves the electrophilic central backbone carbon of the penultimate amino acid residue. This reaction is aided by the intermediacy of an H-bonded intermediate in which the nucleophilic and electrophilic reaction centres are held in proximity in order for the S(N)i cyclisation/cleavage to proceed. The ΔG(reaction) is +184 kJ mol(-1) with the barrier to the S(N)i transition state being +240 kJ mol(-1) at the HF/6-31 + G(d)//AM1 level of theory. A similar phosphate rearrangement from pTyr to side chain CO(2)(-) (of Asp or Glu) may also occur for energised peptide [M-H](-) anions. The reaction is favourable: ΔG(reaction) is -44 kJ mol(-1) with a maximum barrier of +21 kJ mol(-1) (to the initial transition state) when Asp and Tyr are adjacent. The rearranged species R(1)-Tyr-NHCH(CH(2)CO(2)PO(3)H(-))COR(2) (R(1) = CHO; R(2) = OCH(3)) may undergo an S(N)i six-centred cyclisation/cleavage reaction to form the product anion R(1)-Tyr(NH(-)). This process has a high energy requirement [ΔG(reaction) = +224 kJ mol(-1), with the barrier to the S(N)i transition state being +299 kJ mol(-1)]. |
Keywords: | Anions Carboxylic Acids Peptides, Cyclic Phosphotyrosine Molecular Conformation Cyclization Thermodynamics Mass Spectrometry |
Rights: | Copyright © 2011 John Wiley & Sons, Ltd. |
DOI: | 10.1002/rcm.5150 |
Grant ID: | ARC |
Published version: | http://dx.doi.org/10.1002/rcm.5150 |
Appears in Collections: | Aurora harvest IPAS publications |
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