Time-resolved emission spectra of hemoglobin on the picosecond time scale

Enrico Bucci, Henryk Malak, Clara Fronticelli, Ignacy Gryczynski, Gabor Laczko, Joseph R. Lakowicz

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

We used front-face illumination to examine the steady-state and time-resolved emission from the intrinsic tryptophan emission of human hemoglobin (Hb). Experimental conditions were identified which eliminated all contributions of scattered light. The sensitivity obtained using front-face optics was adequate to allow measurement of the wavelength-dependent frequency response of the emission to 2 GHz. The intensity decays displayed pico- and nanosecond components in the emission at all wavelengths from 315 to 380 nm. The contribution of the picosecond component decreased from 72 to 37% over this range of wavelengths. Frequency-domain measurements were used to calculate the time-resolved emission spectra and decay-associated emission spectra. These spectra indicate that the picosecond components of the emission display maxima near 320 nm, whereas the nanosecond components are centered at longer wavelengths near 335 nm. The nanosecond components appear to be due to residual impurities which remain even in highly purified samples of Hb. However, we cannot eliminate the possibility that some of these components are due to Hb itself.

Original languageEnglish
Pages (from-to)187-198
Number of pages12
JournalBiophysical Chemistry
Volume32
Issue number2-3
DOIs
StatePublished - Dec 1988

Keywords

  • Hemoglobin
  • Picosecond spectroscopy
  • Time-resolved emission
  • Tryptophan fluorescence

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