Pressure Effects On The Proximal Heme Pocket In Myoglobin Probed By Raman And Near-Infrared Absorption Spectroscopy

    Authors

    O. Galkin; S. Buchter; A. Tabirian;A. Schulte

    Comments

    Authors: contact us about adding a copy of your work at STARS@ucf.edu

    Abbreviated Journal Title

    Biophys. J.

    Keywords

    MOLECULAR-DYNAMICS SIMULATION; BARRIER HEIGHT DISTRIBUTIONS; CARBON-MONOXIDE BINDING; RESONANCE RAMAN; LIGAND-BINDING; NEUTRON-SCATTERING; BAND-III; PROTEINS; HEMOGLOBIN; SPECTRA; Biophysics

    Abstract

    The influence of high pressure on the heme protein conformation of myoglobin in different ligation states is studied using Raman spectroscopy over the temperature range from 30 to 295 K. Photostationary experiments monitoring the oxidation state marker bands demonstrate the change of rebinding rate with pressure. While frequency changes of vibrational modes associated with rigid bonds of the porphyrin ring are <1 cm(-1), we investigate a significant shift of the iron-histidine mode to higher frequency with increasing pressure (approximate to 3 cm(-1) for Delta P = 190 MPa in Mb). The observed frequency shift is interpreted structurally as a conformational change affecting the tilt angle between the heme plane and the proximal histidine and the out-of-plane iron position. Independent evidence for iron motion comes from measurements of the redshift of band III in the near-infrared with pressure. This suggests that at high pressure the proximal heme pocket and the protein are altered toward the bound state conformation, which contributes to the rate increase for CO binding. Raman spectra of Mb and photodissociated MbCO measured at low temperature and variable pressure further support changes in protein conformation and are consistent with grasslike properties of myoglobin below 160 K.

    Journal Title

    Biophysical Journal

    Volume

    73

    Issue/Number

    5

    Publication Date

    1-1-1997

    Document Type

    Article

    Language

    English

    First Page

    2752

    Last Page

    2763

    WOS Identifier

    WOS:A1997YD84800049

    ISSN

    0006-3495

    Share

    COinS