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INFLUENCE OF HYDRATION ON THE INTERNAL DYNAMICS OF HEN EGG WHITE LYSOZYME IN THE DRY STATE
Author(s) -
Shah Naina K.,
Ludescher Richard D.
Publication year - 1993
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1993.tb09544.x
Subject(s) - lysozyme , chemistry , phosphorescence , relative humidity , aqueous solution , tryptophan , egg white , softening , crystallography , biophysics , chemical physics , biochemistry , thermodynamics , organic chemistry , materials science , fluorescence , amino acid , quantum mechanics , biology , composite material , physics
— Proteins exist in a predominately aqueous solvent environment. Hydration of the protein surface significantly affects many aspects of the protein's structure and function; these effects may be related to the molecular dynamics of the protein. We have examined the influence of hydration on the internal dynamics of hen egg white lysozyme using room‐temperature phosphorescence from the intrinsic tryptophan residues. Powders of lyophilized lysozyme were hydrated in a phosphorimeter using a flow system that allowed for continuous manipulation of relative humidity over the range 0–92%; this system allowed us to directly compare intensity differences that result from changes in hydration. Lysozyme phosphorescence intensity decreased as a function of hydration over the entire relative humidity range; the decrease was not linear but appeared to occur in distinct phases. The phosphorescence intensity decays were multiexponential over the hydration range studied, and hydration had the largest influence on the long lifetime component. These data suggest that the protein exists in multiple, static conformations in the dry state and that water binding to polar (as opposed to charged) sites on the protein surface induces local and/or global softening of the protein structure.