Thermal-induced proteinquake in oxyhemoglobin

• Main Authors: Gevorkian, S. G, Allahverdyan, A. E, Gevorgyan, D. S, Hu, Chin-Kun
• Format: Journal Article
• Language: English
• Published: 02-05-2015
• Subjects: Physics - Soft Condensed Matter; Quantitative Biology - Biomolecules
• DOI: 10.48550/arxiv.1505.00323

Oxygen is released to living tissues via conformational changes of hemoglobin
from R-state (oxyhemoglobin) to T-state (desoxyhemoglobin). The detailed
mechanism of this process is not yet fully understood. We have carried out
micromechanical experiments on oxyhemoglobin crystals to determine the behavior
of the Young's modulus and the internal friction for temperatures between 20 C
and 70 C. We have found that around 49 C oxyhemoglobin crystal samples undergo
a sudden and strong increase of their Young's modulus, accompanied by a sudden
decrease of the internal friction. This sudden mechanical change (proteinquake)
takes place in a partially unfolded state and precedes the full denaturation
transition at higher temperatures. The hemoglobin crystals after the
proteinquake has the same mechanical properies as the initial state at room
temperatures. We conjecture that it can be relevant for explaining the
oxygen-releasing function of native oxyhemoglobin when the temperature is
increased, e.g. due to active sport. The effect is specific for the quaternary
structure of hemoglobin, and is absent for myoglobin with only one peptide
sequence.