Macromolecular Crowding Slows Glutamate Dehydrogenase Kinetics

• DOI: 10.1096/fasebj.2022.36.s1.0r353
• Publication Date: 2022-05-03T08:40:44Z
• Authors: Kristin Slade; Andrea Desrochers; Emily Rundlett; Maddie Schleicher
• Keywords: Macromolecular Crowding

Most of our understanding enzyme kinetics is based on experiments conducted in dilute solution, which does not accurately represent crowded cellular environments. Cells contain high concentrations (300-400g/L) various macromolecules such as proteins, carbohydrates and ribosomes. This crowding reduces the volume solvent available for other molecules solution has previously been shown to impact behavior enzymes. To study these potential consequences, Michaelis-Menten glutamate dehydrogenase (GDH) was monitored presence "crowding agents" dextran, a glucose polymer. Given this enzyme's central role at interface nitrogen carbohydrate metabolism, GDH highly regulated. Our results suggest that may influence regulation. For example, leucine less effective activator dextran. Furthermore, enhances substrate inhibition pH-dependent manner. The resulting effects from were dependent dextran decreased Vmax more with NADP+ cofactor than NAD+ . Both BSA Km but did affect enthalpy (ΔH҂ ) entropy (ΔS҂ activations determined Eyring plots also pH-dependent. Overall, highlight importance studying enzymes especially heavily regulated ones like under conditions realistically mimic environment.