Biophysical Journal 73: 2742-2751 (1997)
© 1997 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Di Iorio, E E Articles by Yu, W Search for Related Content PubMed PubMed Citation Articles by Di Iorio, E E Articles by Yu, W

Dynamic properties of monomeric insect erythrocruorin III from Chironomus thummi-thummi: relationships between structural flexibility and functional complexity.

Laboratorium für Biochemie I, ETH Zurich, Switzerland. diiorio@bc.biol.ethz.ch

ABSTRACT

We have investigated the kinetics of geminate carbon monoxide binding to the monomeric component III of Chironomus thummi-thummi erythrocruorin, a protein that undergoes pH-induced conformational changes linked to a pronounced Bohr effect. Measurements were performed from cryogenic temperatures to room temperature in 75% glycerol and either 0.1 M potassium phosphate (pH 7) or 0.1 potassium borate (pH 9) after nanosecond laser photolysis. The distributions of the low temperature activation enthalpy g(H) for geminate ligand binding derived from the kinetic traces are quite narrow and are influenced by temperature both below and above approximately 170 K, the glass transition temperature. The thermal evolution of the CO binding kinetics between approximately 50 K and approximately 170 K indicates the presence of some degree of structural relaxation, even in this temperature range. Above approximately 220 K the width of the g(H) progressively decreases, and at 280 K geminate CO binding becomes exponential in time. Based on a comparison with analogous investigations of the homodimeric hemoglobin from Scapharca inaequivalvis, we propose a link between dynamic properties and functional complexity.

This article has been cited by other articles:

				S. Cotesta, I. Tavernelli, and E. E. Di Iorio Dynamics of RNase-A and S-Protein: A Molecular Dynamics Simulation of the Transition Toward a Folding Intermediate Biophys. J., October 1, 2003; 85(4): 2633 - 2640. [Abstract] [Full Text] [PDF]

				I. Tavernelli, S. Cotesta, and E. E. Di Iorio Protein Dynamics, Thermal Stability, and Free-Energy Landscapes: A Molecular Dynamics Investigation Biophys. J., October 1, 2003; 85(4): 2641 - 2649. [Abstract] [Full Text] [PDF]

				R. E. Weber and S. N. Vinogradov Nonvertebrate Hemoglobins: Functions and Molecular Adaptations Physiol Rev, April 1, 2001; 81(2): 569 - 628. [Abstract] [Full Text] [PDF]