Author: Privalov, P.L.; Griko YuV; Venyaminov SYu; Kutyshenko, V.P.
Description: The stability of the structure of sperm whale metmyoglobin has been studied in various solutions, in the temperature range -8 degrees C to 100 degrees C, by scanning microcalorimetry, light absorption, circular dichroism, nuclear magnetic resonance spectroscopy and viscosimetry. It has been shown that in 10 mM-sodium acetate solutions (pH 3.5 to 3.9) the protein molecule undergoes a reversible conformational transition into a non-compact disordered state not only when the solution is heated above room temperature but also when it is cooled. In this state the protein does not have a tertiary structure, although it retains some residual ellipticity, which may be caused by the fluctuating alpha-helical conformation of the unfolded polypeptide chain. The disruption of the native protein structure both on cooling (cold-denaturation) and on heating (heat-denaturation) proceeds in an “all-or-none” manner, with a significant and similar increase of the protein heat capacity, but with inverse enthalpic and entropic effects: the enthalpy and entropy of the protein molecule decrease during cold-denaturation and increase during heat-denaturation.
Subject headings: Animals; Calorimetry; Cetacea; Cold Temperature; Hemeproteins; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Metmyoglobin; Protein Denaturation; Spectrum Analysis; Temperature; Thermodynamics; Whales
Publication year: 1986
Journal or book title: Journal of Molecular Biology
Volume: 190
Issue: 3
Pages: 487-498
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Type: Journal Article
Serial number: 1564