As a theoretician, I collaborate on bio-polymer physics with experimental physicists Sasun Gevorkian and Davit Gevorgyan, and a theoretician Chin-Kun Hu. Here are some of our recent papers.
S.G. Gevorkian, A.E. Allahverdyan, D.S. Gevorgyan, W.-J. Ma, C.-K. Hu, Can morphological changes of erythrocytes be driven by hemoglobin? Physica A 508, 608-612 (2018).
Summary:
S.G. Gevorkian, A.E. Allahverdyan, D.S. Gevorgyan and Chin-Kun Hu, Thermal-induced force release in oxyhemoglobin, Scientific Reports, 5, 13064 (2015)
Summary:
Most commonly asked questions in protein research are: what does a protein look like, what does it do, and how does it do it? Although a three dimensional structure at atomic resolution provides a clear answer to the first one, the latter questions concerning protein function are quite problematic. These questions are at the focus of our recent paper. Employing the methods of statistical physics and experiments in the solid state, we try to answer these questions on the example of hemoglobin.
Hemoglobin has an important physiological function: it carries oxygen from the lungs throughout the body allowing us to breathe and live. Hence, since its discovery in 1840, it is one of the most extensively studied proteins. Many of its structural aspects are now clarified in detail: It consists of four globular units linked into a double-dimer tetrameric structure. Each unit can carry one oxygen molecule attached to its heme group. Oxygen is released to living tissues via a cooperative conformational change of hemoglobin from R-state (oxyhemoglobin) to T-state (desoxyhemoglobin). However, certain important aspects of this oxygen release are not understood. In particular, it is not accounted that the oxygen release takes place in essentially different conditions, as compared to oxygen consumption: the release takes a much smaller time, and is likely to have a targeted character, i.e. tissues in need of oxygen get it easier (faster).
In our paper we make a step towards uncovering hidden aspects of hemoglobin functioning. We studied mechanical response (Young's modulus and internal friction) of human and horse hemoglobin crystals and saw that in its partially unfolded state the hemoglobin responds to heating by a sudden release of force and a subsequent jump of the Young's modulus. This mechanical force release in response to heating was not expected, because in simple materials higher temperatures lead to diminishing mechanic features. We argued that the effect relates to certain slowly relaxing degrees of freedom of the quaternary structure that accumulate energy during heating and then suddenly release it at a well-defined temperature that is specific for hemoglobin. This result can be relevant for explaining possible mechanisms of fast oxygen release in tissues that could proceed via increase of local temperature.