Picosecond resolution of oxytocin tyrosyl fluorescence by 2 GHz frequency-domain fluorometry

Joseph R. Lakowicz, Gabor Laczko, Ignacy Gryczynski

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


The technique of frequency-domain fluorometry has been extended to 2000 MHz using the harmonic content of a picosecond laser source and a microchannel plate photomultiplier tube. This new instrument was used to resolve complex subnanosecond intensity and anisotropy decays of the tyrosyl emission of oxytocin. The intensity decay was found to contain at least three exponential components, 80, 359 and 927 ps. The anisotropy analysis revealed a 29 ps torsional motion of the tyrosine residue as well as a 454 ps overall rotational correlation time. The time resolution of this method should permit the comparison of experimental results with theoretical models for motions of proteins.

Original languageEnglish
Pages (from-to)97-100
Number of pages4
JournalBiophysical Chemistry
Issue number2
StatePublished - Jul 1986


  • Anisotropy
  • Fluorescence spectroscopy
  • Frequency-domain fluorometry
  • Molecular dynamics
  • Oxytocin
  • Tyrosine fluorescence


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