Investigating the Structural, Functional, and Biochemical Properties of PPi -dependent PEPCK Paralogs from Entamoeba histolytica
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Published:2023-12-21
Issue:2
Volume:2
Page:52-62
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ISSN:2832-5958
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Container-title:Cornell Undergraduate Research Journal
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language:
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Short-container-title:CURJ
Author:
Balamurali Siddhi
Abstract
Phosphoenolpyruvate carboxykinase (PEPCK) is an important metabolic enzyme which functions to interconvert oxaloacetic acid (OAA) and phosphoenolpyruvate (PEP) in the Krebs cycle, a key process of generating cellular energy. There exist three known classes of PEPCK - two of which are nucleotide-dependent, using ATP and GTP. Very little is known about the third, PPi-dependent PEPCK. Comparing classes, nucleotide-dependent PEPCKs are both functionally and structurally similar (~60-70 kDa) whereas PPi-dependent PEPCK bears significant functional and structural differences (~130 kDa). This presented work investigates PPi-dependent PEPCK from a human parasite Entamoeba histolytica (EhPEPCK). It is unique from previous work done on another homolog from Propionibacterium freudenreichii (PfPEPCK) in that there are three paralogs instead of one. This suggests increased complexity in function and regulation. This work has determined that the interaction between EhPEPCK paralogs gives rise to dimers and heterotrimers, and certain interactions show substrate induced inhibition. Kinetic measurements were completed to determine the metal cofactor of EhPEPCKs, and to determine the kinetic consequences of the aforementioned oligomeric states. The experiments support the conclusion that aggregation causes substrate inhibition, and that dimers are more active than trimers.
Publisher
Cornell University Library
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