Softening of the packing density of horseradish peroxidase by a H-donor bound near the heme pocket.
We use pressure tuning of spectral holes to estimate the compressibility of protein molecules by optical means. We found that the compressibility of mesoporphyrin-substituted horseradish peroxidase increases by a factor of three when it incorporates small aromatic H-donor molecules that bind in the vicinity of its heme pocket. Such a dramatic softening of its packing density corresponds to a jump from a compressibility range characteristic for the solid state into that characteristic for liquids.
Institute of Biophysics, Semmelweis Medical University, Budapest, H-1444, Hungary.
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J
Fidy
J M
JM
Vanderkooi
J
J
Zollfrank
J
J
Friedrich