|
author |
Joel Asabi Moses
| title |
Investigating the Effects of pH and Salt Concentration on Substrate Inhibition of Yeast Aldo-Keto Reductase 163
| abstract |
Aldo-keto reductases (AKRs) are a broad superfamily of NADPH-dependent oxidoreductases
capable of catalyzing the reduction of many carbonyl compounds into alcohols in living systems
and industrial settings. Most studied AKRs exhibit substrate saturation where they experience
typical Michaelis-Menten kinetics with their substrates. However, a novel AKR isolated from
ancient amber called AKR 163 experiences a phenomenon called substrate inhibition in the
presence of electron withdrawing substrates such as ethyl 4-chloroacetoacetate (E4ClAA). This
characteristic is often undesirable biologically and industrially since it leads to poor product
yields. Unfortunately, there are few studies that aim to alleviate substrate inhibition despite its
disadvantages. For these reasons, researchers used AKR 163 as a model enzyme to test the
effects of pH on substrate inhibition. They found that decreasing pH reduced substrate inhibition.
However, these studies used two types of buffers to gather data from a wide range of pHs, which
could have led to inconsistent results. Similarly, researchers have also tested the effects of
exogenous salt ions on substrate inhibition and found that adding salt decreases inhibition. Given
the successes and shortcomings of these researchers, I combined these ideas to observe and
explain the effects of salt ions and pH changes together on substrate inhibition using an ACES
buffer system and E4ClAA as the substrate. My results confirm that lowering pH and adding salt
decrease substrate inhibition individually. Furthermore, the lowest pH trial (pH 6) with 1M NaCl
showed almost no signs of inhibition with up to 6 mM of substrate, and the plot resembled a
Michaelis-Menten curve. These results indicate that substrate inhibition can be almost
completely inhibited under those conditions.
| school |
The College of Liberal Arts, Drew University
| degree |
B.S. (2024)
|
advisor |
Adam Cassano
|
full text | JMoses.pdf |
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