An oligomer usually refers to a macromolecular complex formed by non-covalent interactions of monomers. Several thermophilic proteins are oligomers. The significance of oligomerization of individual proteins for stability at higher temperature is of prime importance for understanding evolution and increasing industrial productivity. The functional form of Thermus thermophilius isopropylmalate dehydrogenase (IPMDH), a widely studied protein to understand the factors affecting the thermal stability of a protein is a dimer, a simplest oligomer. To decipher the relationship between the effects of oligomerization on thermal stability of a protein, we have applied all-atom molecular mechanics approach by analyzing how temperature effects dynamics of a subunit in the presence and absence of another subunit in dimeric (SS) and monomeric forms (SA), respectively, before its denaturation begins. Comparing the difference in overall dynamic structural aspects at two different temperatures, 300 K and 337 K. Analysis of root mean square deviation (RMSD), root mean square fluctuations (RMSF) and Cα-Cα distance with an increase in temperature from 300 K to 337 K for a total of 0.2 μs reveals higher thermal stability of the dimer as compared to monomer. In contrast to dimeric form, the monomer is relatively stable at 300 K but cannot withstand the structural stability at 337 K leading to loosening of intramolecular interactions with maximum fluctuation at B23–B24 within a subunit. Energetic and structural properties indicate that B24–B24’ is the major contributor to maintaining subunit-subunit interaction at 337 K. Correlation between the favorable interaction energy (IE) with the minimal perturbance in Cα atoms of domain 2 in a subunit in the presence of another subunit enhances the rigidity of the domain with subunit-subunit interaction. Overall, the study indicates that the dimeric over monomeric form enhances the protein’s thermal stability and not all major subunit interacting regions contribute equally in maintaining the former.

低聚物通常是指由单体的非共价相互作用形成的大分子复合物。几种嗜热蛋白是寡聚体。单个蛋白寡聚化对于高温下稳定性的重要性对于理解进化和提高工业生产率至关重要。嗜热栖热菌的功能形式异丙基苹果酸脱氢酶（IPMDH）是一种广泛研究的蛋白质，可理解影响蛋白质热稳定性的因素，它是二聚体，一种最简单的寡聚物。为了解释寡聚化对蛋白质热稳定性的影响之间的关系，我们通过分析温度如何影响存在和不存在二聚体（SS）和单体形式的另一个亚基的温度对一个亚基动力学的影响，应用了全原子分子力学方法。 （SA）分别在其变性开始之前。比较两个不同温度（300 K和337 K）下整体动态结构方面的差异。分析温度从300 K升高到200 K时的均方根偏差（RMSD），均方根波动（RMSF）和Cα-Cα距离337 K，总计0。2μs表明，与单体相比，二聚体具有更高的热稳定性。与二聚体形式相反，该单体在300 K下相对稳定，但在337 K下不能承受结构稳定性，从而导致分子内相互作用的松散，在亚基内B23–B24处的波动最大。能量和结构性质表明，B24–B24'是在337 K维持亚基-亚基相互作用的主要贡献者。在存在亚基的情况下，亚基中域2的Cα原子的有利相互作用能（IE）与最小扰动之间的相关性。另一个亚基通过亚基-亚基相互作用增强了结构域的刚性。总体，