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Trehalose Prevents Myoglobin Collapse and Preserves Its Internal Mobility G. Madhavi Sastry and Noam Agmon*

Summary: Trehalose Prevents Myoglobin Collapse and Preserves Its Internal Mobility
G. Madhavi Sastry and Noam Agmon*
Department of Physical Chemistry and the Fritz Haber Research Center, The Hebrew UniVersity, Jerusalem 91904, Israel
ReceiVed October 17, 1996; ReVised Manuscript ReceiVed January 23, 1997X
ABSTRACT: A quantitative model, which involves diffusion on a temperature-dependent potential, is utilized
to analyze the time-dependence of geminate CO recombination to sperm whale myoglobin in a trehalose
glass and the accompanying spectral shifts. Most of the recombination is inhomogeneous. This is due
to higher geminate reactivity rather than slower protein relaxation. A fraction of the hemes undergoes
relaxation with a concomitant increase in the barrier height for recombination. The activation energy for
conformational diffusion (relaxation) is considerably lower than in glycerol/water. "Protein collapse",
manifested in glycerol/water by a decrease in the equilibrium conformational separation between the bound
and deoxy states, is completely prevented in trehalose. We postulate that the high internal viscosity in
glycerol/water is due to dehydration of the heme pocket. Trehalose prevents the escape of the few vital
internal water molecules and thus preserves the internal lability of the protein. This might be important
in understanding the ability of trehalose to protect against the adverse effects of dehydration.
Water is essential for normal protein function (Edsall &
McKenzie, 1983; Rupley & Careri, 1991; Rand, 1992).
Dehydration can lead to sizable, partially irreversible, con-
formational changes in some proteins (Prestrelski et al.,


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


Collections: Chemistry