Temperature dependence of the spin S=1/2 fluctuation rate and the low-spin versus high-spin transition in native chloroperoxidase

C. E. Schulz, P. Osmulski, Y. M. Xia, P. G. Debrunner

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

We analyzed two preparations of native, low-spin ferric chloroperoxides as a function of temperature with the following results. (i) The spin lattice transition rate W(T) is relative slow, following a power law W=0.035 (T/K)4.98 (rad/s) for one of the samples. (ii) The quadrupole splitting is strongly temperature dependent, dropping from |δEQ| ∼ 2.94 mm/s at 100 K to ∼2 mm/s at 250 K. (iii) Starting at 190 K, the low-spin heme iron in frozen adqueous solution converts reversibly to a high-spin form, reaching ∼40% high-spin at 250 K. The two forms appear to be in thermal equilibrium, (iv) Optical data indicate that in a 70% glycerol glass, the conversion starts at lower temperature and reaches ∼50% highspin at 190 K.

Original languageEnglish (US)
Pages (from-to)865-874
Number of pages10
JournalHyperfine Interactions
Volume91
Issue number1
DOIs
StatePublished - Dec 1 1994
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Nuclear and High Energy Physics
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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