Direct characterisation by electrospray ionisation mass spectroscopy of mercuro-polypeptide complexes after deprotection of acetamidomethyl groups from protected cysteine residues of synthetic polypeptides

Reinhard I. Boysen, Milton T W Hearn

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In this paper, we describe a rapid procedure to characterise the products generated in the presence of mercuric salts following removal of the acetamidomethyl (Acm)-protecting group from cysteine residues of synthetic polypeptides prepared by solid-phase peptide synthesis (SPPS) methods. In particular, electrospray ionisation mass spectrometry (ESI-MS) procedures have been employed to characterise the mercuro-polypeptide products related to the ribosomal L36 protein isolated from the bacterium Thermus thermophilus. The results demonstrate that very stable mercuro-polypeptide complexes can form under standard conditions of deprotection involving Hg2+ salts in the presence of a reductant such as β-mercaptoethanol. Metal ion exchange effects involving other divalent metal ions, such as Co2+ or Zn2+, can also be monitored by similar procedures, thus permitting the relative affinity and selectivity for metal ion-polypeptide interactions to be qualitatively assessed. Since the Thermus thermophilus ribosomal L36 protein contains a putative zinc finger binding CCCH motif, these procedures enable the formation of metal-ion complexes of synthetic polypeptides related to this structural motif to be directly examined. (C) 2000 Elsevier Science B.V.

Original languageEnglish
Pages (from-to)157-168
Number of pages12
JournalJournal of Biochemical and Biophysical Methods
Issue number2
Publication statusPublished - 11 Sept 2000


  • Acetamidomethyl group
  • Deprotection
  • Electrospray ionisation mass spectrometry
  • ESI-MS
  • Metal complexes
  • Ribosomal proteins
  • SPPS
  • Synthetic cysteinyl polypeptides
  • Thermus thermophilus

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