For this honors thesis, the thermostability of malate dehydrogenase is analyzed to answer a gnawing question of the ability of organisms to thrive in an extreme environment. Thermophilic bacteria are living organisms that exist in what are considered “extreme” temperatures using mesophilic organisms – such as humans – as the narrow standard for “normal” living conditions. To better understand how thermophilic bacteria can withstand the extreme environments they live in, we focused on determining how increased or decreased enzyme thermostability correlates with other denaturing conditions in a classic enzyme assay. The structural components of the enzymes will determine the cause of stability of these unique organisms. A typical enzyme will increase its activity – or functionality – as the temperature increases until it reaches the optimum temperature of reactivity where the enzyme works at its maximum efficiency. After this point, the bonds holding the enzyme in its highly specific structure begin to break. When the enzyme loses its structure, it loses its functionality. A normal mesophilic enzyme will function between roughly 25 and 45°C. Thermophilic enzymes are especially interesting due to their ability to maintain structure as well as high efficiency at temperatures exceeding the typical optimum temperature range – even up to temperatures of 200 °C. We measured the activity of malate dehydrogenase from both thermophilic and mesophilic bacteria in the presence and absence of chaotropic agents showing a differential stability that could be exploited for resolving the basic science question behind thermostability, for industrial uses, and for medical uses. This thesis was used as undergraduate research experience to be better prepared for graduate school in a chemistry doctorate program.
Semester/Year of Award
Martin L. Brock
Restricted Access Thesis
Macke, Amanda C., "Characterizing Thermophiles: A Study of Thermostability in Malate Dehydrogenase" (2018). Honors Theses. 547.