What would happen to an enzyme if the temperature and pH changed significantly beyond the enzymes optimum level

Answer 1

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Enzymes are catalysts, but the major property is that they are proteins. So the structure of the tertiary protein such as an enzyme has different bonds that hold it to maintain its conformation (structural shape and size). These bonds can be classified as covalent and noncovalent bonds. The covalent bonds are the bonds between atoms that make up the primary structure where's the noncovalent are basically more like interactions between primary structures, which then form or fold into secondary, then tertiary and quaternary structures.

With that being said, we now understand that there are different factors that may affect the structure of an enzyme. These are mainly 3: 1) Temperature, 2) pH, and 3) substrate. I will focus on temperature since its your inquiry, kindly message me for more.

Increase in temperature will increase the kinetic energy of particles in a substance. Kinetic energy (kE) is energy possessed in motion. So increase in kE will increase the movement of particles, which cause the randomness. The degree of randomness of particles in a substance is what we call entropy. Therefore, increase in temperature, increase kE which increase entropy. So, if temperature is increase the randomness thus also increasing the heat energy. heat energy will increase conformational flexing (size and shape changes) of the enzyme. If the temperature is increased beyond optimum level then the noncovalent bonds/interactions will be disrupted and enzyme protein structure will be unfolded. The process of unfolding is called denaturation, so they are denatured. If the confirmation is changed then therefore the active site is disrupted and so the substrate can not attach to enzyme active site. Therefore no enzyme reaction will occur. Bottomline: increase in temperature, increases enzyme activity unlike optimum level (45-55C) is reached. Beyond optimum rate of reaction will fall.

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Answer 2

This will be long, here you go!

There are different options. Temperature might drop below the optimum level. Enzyme structure would not be affected by the change however the rate of reaction that the enzyme catalyzes would decrease because all the molecules (including the enzyme) would start moving slower in the environment. This means the likelihood of interactions between the enzyme and its substrate would decrease causing the rate to decrease. If pH also changes along with the drop in the temperature, enzyme structure would change and enzyme would be denatured. Here is why. The enzyme structure is held together by interactions between the side chains of the amino acids. Some of the side chains' properties change with pH. For example, some side chains are positively charged in neutral pH. This side chain will become negatively charged at some point as you increase the pH. When there is a change in the amino acid properties, the interactions that hold the structure of an enzyme will change and the enzyme will not keep its original form and take up a different shape which highly likely will be an ineffective shape. At this point, enzyme is said to be "denatured".

Temperature might also increase and this will disrupt the interactions between amino acids (such as H bonds, Van der Waals interactions, etc.) and enzyme will not be able to keep its natural shape and will become "denatured". The rate of reaction in this environment will either significantly drop (despite the more frequent interactions between enzyme and the substrate due to faster movement of molecules in the environment) or the reaction will stop depending on how high the temperature is. pH changes at this point becomes insignificant as rising temperature already denatured the enzyme. It only contributes to the degree of denaturation.

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