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Human myoglobin recognition of oxygen: Dynamics of the energy landscape

Wang, Yuhong and Baskin, J. Spencer and Xia, Tianbing and Zewail, Ahmed H. (2004) Human myoglobin recognition of oxygen: Dynamics of the energy landscape. Proceedings of the National Academy of Sciences of the United States of America, 101 (52). pp. 18000-18005. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:WANpnas04

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Abstract

Femtosecond to nanosecond dynamics of O2 rebinding to human WT myoglobin and its mutants, V68F and I107F, have been studied by using transient absorption. The results are compared with NO rebinding. Even though the immediate environment around the heme binding site is changed by the mutations, the picosecond geminate rebinding of oxygen is at most minimally affected. On the other hand, the V68F (E11) mutation causes drastic differences in rebinding on the nanosecond time scale, whereas the effect of the I107F (G8) mutation remains relatively small within our 10-ns time window. Unlike traditional homogeneous kinetics and molecular dynamics collisional simulations, we propose a "bifurcation model" for populations of directed and undirected dynamics on the ultrafast time scale, reflecting the distribution of initial protein conformations. The major mutation effect occurs on the time scale on which global protein conformational change is possible, consistent with transitions between the conformations of directed and undirected population playing a role in the O2 binding. We discuss the relevance of these findings to the bimolecular function of the protein.


Item Type:Article
Additional Information:Contributed by Ahmed H. Zewail, November 15, 2004. We acknowledge the contribution of Dr. Qing-Bin Lu (California Institute of Technology) in developing the experimental apparatus used for the measurements reported here. This work was supported by the National Science Foundation.
Subject Keywords:femtobiology, molecular recognition, myoglobin, carbonmonoxymyoglobin, oxymyoglobin, nitrosylmyoglobin, deoxymyoglobin
Record Number:CaltechAUTHORS:WANpnas04
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:WANpnas04
Alternative URL:http://dx.doi.org/10.1073/pnas.0408379102
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:493
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:11 Jul 2005
Last Modified:14 Nov 2014 19:18

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