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Stability of hemoglobin Chironomus thummi thummi in the system of solvents water- -ethylene glycol. Studies of mechanism of denaturation of Hb CTT
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Abstracts
Qualitative analysis of the effect of ethylene glycol (EG) on the stability of the native
structure of monomeric and dimeric methemoglobins isolated from larvae of Chironomus
thummi thummi (CTT Hb) was performed by measurements of thermodynamic parameters of
denaturation employing the equilibrium method. Results of denaturation studies at various
pH conditions demonstrate that the stability of dimeric CTT Hb is close to that of human
Hb while monomeric components show a highter lability. The dependence of denaturation
enthalpy on the EG concentration is slightly different for monomeric and dimeric components.
For dimeric Hb a considerable decrease of denaturation energy was found already at very
low EG concentration which is probably due to the disturbance of interaction between the
dimeric - forming chains and, as a consequence, to their dissociation. The futher course of
the curves is similar for both Hb deriveratives: an increase in the denaturation energy is
observed, peaking at the EG molar fraction of 0.04-0.05, folowed by its rapid decrease. The
obtained results are in agreement with the following hypothesis. The structal and dynamic
stability of globular proteins is controlled by interactions with the surrounding water molecules. Addition of an organic solvent, possessing both hydrophilic and hydrophobic
properties as EG, to the medium, disturbs the native protein conformation by change of the
structure of its hydration shell. At appropriate concentrations, EG makes the protein to
acquire the supernative structure which is reflected by changes in absorption spectra in the
UV range demonstrating alterations in the surrounding of the hydrophobic residues. Highter
EG concentrations are sufficient to form a new hydration shell of the protein molecule
enducing its different special organization.
structure of monomeric and dimeric methemoglobins isolated from larvae of Chironomus
thummi thummi (CTT Hb) was performed by measurements of thermodynamic parameters of
denaturation employing the equilibrium method. Results of denaturation studies at various
pH conditions demonstrate that the stability of dimeric CTT Hb is close to that of human
Hb while monomeric components show a highter lability. The dependence of denaturation
enthalpy on the EG concentration is slightly different for monomeric and dimeric components.
For dimeric Hb a considerable decrease of denaturation energy was found already at very
low EG concentration which is probably due to the disturbance of interaction between the
dimeric - forming chains and, as a consequence, to their dissociation. The futher course of
the curves is similar for both Hb deriveratives: an increase in the denaturation energy is
observed, peaking at the EG molar fraction of 0.04-0.05, folowed by its rapid decrease. The
obtained results are in agreement with the following hypothesis. The structal and dynamic
stability of globular proteins is controlled by interactions with the surrounding water molecules. Addition of an organic solvent, possessing both hydrophilic and hydrophobic
properties as EG, to the medium, disturbs the native protein conformation by change of the
structure of its hydration shell. At appropriate concentrations, EG makes the protein to
acquire the supernative structure which is reflected by changes in absorption spectra in the
UV range demonstrating alterations in the surrounding of the hydrophobic residues. Highter
EG concentrations are sufficient to form a new hydration shell of the protein molecule
enducing its different special organization.
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1996
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author
author
References
Document Type
Publication order reference
Identifiers
URI
http://hdl.handle.net/11089/14130
YADDA identifier
bwmeta1.element.hdl_11089_14130
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