Quantitative analysis of total correlation spectra: Application to small biomolecules

F. Fogolari, G. Esposito, S. Cattarinussi, P. Viglino

Research output: Contribution to journalArticle

Abstract

The peak intensities of total correlation spectra are intimately related to J-coupling constants, which in turn are related to local geometry. Knowledge of J values is therefore useful in determining molecular structure. In the past, the complexity of the time development of total correlation cross-peaks has hindered their use in extracting structural information. This paper reviews the relevant quantum-mechanical equations. The series expansion of the density matrix for the most general spin-1/2 system undergoing isotropic mixing offers a convenient approximation that can be exploited to evaluate the extent of net transfer as a function of J values. A method for evaluating J-coupling constants from total correlation spectra of small biomolecules is presented as an application and as an illustration of the theory. Peak amplitude quantitation of short-mixing-time spectra provides tentative estimates of scalar couplings (accurate up to the third order of the series expansion as a function of mixing time). These estimates can be further refined by fitting the experimental data with theoretical transfers obtained by a full density matrix calculation. An experimental illustration of the method is given for a nucleic acid and a coenzyme system, although the conclusions should hold for every similar spin system.

Original languageEnglish (US)
Pages (from-to)229-251
Number of pages23
JournalConcepts in Magnetic Resonance
Volume8
Issue number4
StatePublished - Jan 1 1996

ASJC Scopus subject areas

  • Chemistry(all)
  • Spectroscopy
  • Physical and Theoretical Chemistry

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