Peroxidase is an enzyme found in many organisms, from plant to humans. The function of peroxidase is to break down hydrogen peroxide, which is a toxin produced as a byproduct when oxygen is produced during respiration. Lactoperoxidase is found in human tissues, glands, and secretions, such as milk, tears, and saliva. It plays an important role in defense against pathogenic microorganisms in the intestinal tract of newborn infants and a protective role in sterility of secretions for the respiratory tract. For lactoperoxidase to function properly, thiocyanate is needed.


A- Identify two examples of environmental factors that may impact salivary peroxidase activity. Describe how each of the environmental factors would affect the reaction rate of the enzyme.

B- Predict the effects of defects in the thiocyanate transport channels. Provide reasoning to justify your prediction.

Answer:

A) two examples of environmental factors that may impact salivary peroxidase activity are pH and temperature. All enzymes have an ideal pH range. When the environment has a pH in that specific range, the enzymatic reaction rate will be the fastest. However, when the environment deviates from the pH range, the enzyme's reaction rate will be slower. Furthermore, when the pH is too far off that ideal pH range, then the salivary peroxidase may denature and unravel, due to it being a protein. Another factor is temperature. When temperature is higher, the reaction rate increases. However, when the temperature is lower, the reaction rate decreases. However, when the temperature gets too high, then the enzyme may denature.

B) The effects of defects in the thiocyanate transport channels would be for lactoperoxidase to not be able to function properly, causing defects in the defense against pathogenic microorganisms in the intestinal tract of newborn infants and defects in sterility of the secretions for the respiratory tract.  

In order for lactoperoxidase to function properly, thiocyanate is necessary. Because of this, Therefore, thiocyanate is likely a cofactor, allowing for lactoperoxidase to function.

Because of this, if the thiocyanate transport channels are defective, thiocyanate can likely not reach the lactoperoxidase, and can therefore not bind to it. This defect in the transport channels would mean that thiocyanate cannot carry out its necessary function of activating lactoperoxidase.

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