Comparison of 15N- and 13C-determined parameters of mobility in melittin

Lingyang Zhu, Franklyn G. Prendergast, Marvin D. Kemple

Research output: Contribution to journalReview articlepeer-review

10 Scopus citations

Abstract

Backbone and tryptophan side-chain mobilities in the 26-residue, cytolytic peptide melittin (MLT) were investigated by 15N and 13C NMR. Specifically, inverse-detected 15NT1 and steady-state NOE measurements were made at 30 and 51 MHz on MLT at 22°C enriched with 15N at six amide positions and in the Trp19 side chain. Both the disordered MLT monomer (1.2 mM peptide at pH 3.6 in neat water) and α-helical MLT tetramer (4.0 mM peptide at pH 5.2 in 150 mM phosphate buffer) were examined. The relaxation data were analyzed in terms of the Lipari and Szabo model-free formalism with three parameters: τm, the correlation time for the overall rotation; S2, a site-specific order parameter which is a measure of the amplitude of the internal motion; and τe, a local, effective correlation time of the internal motion. A comparison was made of motional parameters from the 15N measurements and from 13C measurements on MLT, the latter having been made here and previously [Kemple et al. (1997) Biochemistry, 36, 1678-1688]. τm and τe values were consistent from data on the two nuclei. In the MLT monomer, S2 values for the backbone N-H and Cα-H vectors in the same residue were similar in value but in the tetramer the N-H order parameters were about 0.2 units larger than the Cα-H order parameters. The Trp side-chain N-H and C-H order parameters, and τe values were generally similar in both the monomer and tetramer. Implications of these results regarding the dynamics of MLT are examined.

Original languageEnglish (US)
Pages (from-to)135-144
Number of pages10
JournalJournal of Biomolecular NMR
Volume12
Issue number1
DOIs
StatePublished - 1998

Keywords

  • Internal dynamics
  • Model-free approach
  • Order parameters
  • Peptides
  • Relaxation

ASJC Scopus subject areas

  • Biochemistry
  • Spectroscopy

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