Department of Botany, Bhaskaracharya College of Applied Sciences, University of Delhi, Delhi, India.
Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India.
Int J Biol Macromol. 2021 Apr 30;177:229-240. doi: 10.1016/j.ijbiomac.2021.02.102. Epub 2021 Feb 16.
Organic osmolytes are known to play important role in stress protection by stabilizing macromolecules and suppressing harmful effects on functional activity. There is existence of several reports in the literature regarding their effects on structural, functional and thermodynamic aspects of many enzymes and the interaction parameters with proteins have been explored. Osmolytes are compatible with enzyme function and therefore, can be accumulated up to several millimolar concentrations. From the thermodynamic point of view, osmolyte raises mid-point of thermal denaturation (T) of proteins while having no significant effect on ΔG° (free energy change at physiological condition). Unfavorable interaction with the peptide backbone due to preferential hydration is the major driving force for folding of unfolded polypeptide in presence of osmolyte. However, the thermodynamic basis of stress protection and origin of compatibility paradigm has been a debatable issue. In the present manuscript, we attempt to elaborate the origin of stress protection and compatibility paradigm of osmolytes based on the effect on thermodynamic stability of proteins. We also infer that protective effects of osmolytes on ΔG° (of proteins) could also indicate its potential involvement in unfolded protein response and overall stress biology on macromolecular level.
有机渗透物通过稳定大分子和抑制对功能活性的有害影响，已知在应激保护中发挥重要作用。文献中有许多关于它们对许多酶的结构、功能和热力学方面的影响的报道，并探索了与蛋白质的相互作用参数。渗透物与酶功能兼容，因此可以积累到几毫米的浓度。从热力学的角度来看，渗透物提高了蛋白质热变性的中点（T），而对ΔG°（生理条件下的自由能变化）没有显著影响。由于优先水合作用与肽骨架的不利相互作用是在渗透物存在下展开的未折叠多肽折叠的主要驱动力。然而，应激保护的热力学基础和相容性范例的起源一直是一个有争议的问题。在本文中，我们试图根据蛋白质热力学稳定性的影响，详细阐述渗透物应激保护和相容性范例的起源。我们还推断，渗透物对ΔG°（蛋白质）的保护作用也可能表明它可能参与未折叠蛋白反应和大分子水平上的整体应激生物学。
