These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Direct observations of ligand dynamics in hemoglobin by subpicosecond infrared spectroscopy.
    Author: Anfinrud PA, Han C, Hochstrasser RM.
    Journal: Proc Natl Acad Sci U S A; 1989 Nov; 86(21):8387-91. PubMed ID: 2554314.
    Abstract:
    The photodissociation of CO from HbCO at ambient temperature is studied by means of a femtosecond IR technique. The bleaching of the FeCO absorption and the appearance of a new IR absorption near that of free CO are both observed at 300 fs after optical excitation. The bleach does not recover on the time scale of a few picoseconds but does recover by approximately 4% within 1 ns, which suggests that a barrier to recombination is formed within a few picoseconds. The CO spectrum does not change significantly between 300 fs and 1 ns, suggesting that the CO quickly finds some locations in the heme pocket that are not more than a few angstroms from the iron. The de-ligated CO appears in its ground vibrational level. There is evidence that 85 +/- 10% of this CO remains in the heme pocket at 1 ns; it probably resides there for 50 ns. The flow of excess vibrational energy from the heme to the solvent was directly observed in the IR experiments. The heme cools within 1-2 ps while thermal disruption of the surrounding solvent structure requires approximately 30 ps.
    [Abstract] [Full Text] [Related] [New Search]