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Biophysical Journal Volume 66 May 1994 1612-1622 The Transition from Inhomogeneous to Homogeneous Kinetics in CO
 

Summary: Biophysical Journal Volume 66 May 1994 1612-1622
The Transition from Inhomogeneous to Homogeneous Kinetics in CO
Binding to Myoglobin
Noam Agmon, Wolfgang Doster, and Frank Post
Department of Physical Chemistry and the Fritz Haber Research Center, The Hebrew University, Jerusalem 91904, Israel; Technische
Universitat Munchen, Physikdepartment El 3, W-8046 Garching, Germany
ABSTRACT Heme proteins react inhomogeneously with ligands at cryogenic temperatures and homogeneously at room
temperature. We have identified and characterized a transition from inhomogeneous to homogeneous behavior at intermediate
temperatures in the time dependence of CO binding to horse myoglobin. The turnover is attributed to a functionally important
tertiary protein relaxation process during which the barrier increases dynamically. This is verified by a combination of theory
and multipulse measurements. A likely biological significance of this effect is in the autocatalysis of the ligand release process.
INTRODUCTION
Ligand binding to myoglobin (Mb) is a model biophysical
reaction, extensively studied over a large range of times and
temperatures (Austin et al., 1975; Doster et al., 1982, 1989,
1990; Ansari et al., 1985, 1987, 1992; Ormos et al., 1990;
Steinbach et al., 1991; Young et al., 1991; Campbell et al.,
1987; Petrich et al., 1991; Gibson et al., 1992; Srajer et al.,
1991; Tian et al., 1992; Hong et al., 1991; Post et al., 1993).
In the experimental data of Fig. 1, horse Mb-CO is photo-

  

Source: Agmon, Noam - Institute of Chemistry, Hebrew University of Jerusalem

 

Collections: Chemistry