3. What organisms can phenylalanine hydroxylase be found within? Describe the resulting product and why it is important for
the organism that uses it.
4. Why are the reactants (substrates) changed? Are they harmful in some way? Are they needed to produce
something important? Draw a picture of the substrates.
5. What would happen if phenylalanine hydroxylase did not exist?
6. Why is it important for enzymes to remain unchanged after the product is made?
3. Phenylalanine hydroxylase is an enzyme that can be found in a variety of organisms, including plants, fungi, bacteria, and animals. This enzyme plays a crucial role in converting the amino acid phenylalanine into another amino acid called tyrosine. This conversion is important because tyrosine is an essential building block for the synthesis of various molecules in the organism, including neurotransmitters (such as dopamine, epinephrine, and norepinephrine), hormones, and pigment molecules. Therefore, having phenylalanine hydroxylase is essential for the proper growth, development, and functioning of the organism.
To find more specific information about the organisms in which phenylalanine hydroxylase can be found, you can refer to scientific research articles, textbooks, or databases that specialize in enzyme information, such as the UniProt database or the BRENDA enzyme database. These resources provide detailed information about enzyme distribution across different organisms.
4. The reactants, also known as substrates, undergo changes during a chemical reaction due to the action of enzymes. Enzymes facilitate and accelerate chemical reactions by lowering the activation energy required for the reaction to occur. In other words, enzymes make it easier for the substrates to undergo a chemical transformation.
The substrates are not necessarily harmful, but they need to be transformed or converted into something else for various reasons. For example, in the case of phenylalanine hydroxylase, the substrate phenylalanine is not harmful itself, but if it accumulates excessively in the body, it can lead to a condition called phenylketonuria (PKU). PKU is a genetic disorder in which the body cannot properly metabolize phenylalanine, leading to its accumulation in the blood. This accumulation can cause severe neurological problems, intellectual disabilities, and other health issues. Therefore, the conversion of phenylalanine by phenylalanine hydroxylase is necessary to prevent harmful levels of phenylalanine in the organism.
Here is a simple diagram representing the substrates in the context of phenylalanine hydroxylase:
```
Phenylalanine + O2
↓
Phenylalanine hydroxylase
↓
Tyrosine + H2O
```
5. If phenylalanine hydroxylase did not exist or was not properly functioning, the conversion of phenylalanine into tyrosine would be impaired. This would lead to an accumulation of phenylalanine in the body, as mentioned earlier. In the case of a genetic disorder like PKU, where phenylalanine hydroxylase is defective or absent, the accumulation of phenylalanine can cause serious health problems. The excess phenylalanine cannot be properly metabolized, leading to disruption of normal brain development and function. This can result in intellectual disabilities, developmental delays, seizures, behavioral and psychiatric issues, and other complications. Therefore, the absence or dysfunction of phenylalanine hydroxylase can have severe consequences for the organism.
6. It is important for enzymes to remain unchanged after the product is made because enzymes are catalysts in chemical reactions. They facilitate the reaction by lowering the activation energy requirement and increasing the reaction rate, but they are not consumed or altered in the process.
Enzymes are typically large protein molecules with specific three-dimensional structures that enable them to bind substrates and catalyze reactions. After the reaction occurs, the enzyme releases the product(s) and is ready to catalyze the next reaction with other substrates.
If the enzyme were to be changed or consumed during the reaction, it would not be available to catalyze subsequent reactions, leading to a loss of catalytic efficiency. Enzymes function optimally when they can undergo multiple catalytic cycles, serving as reusable and efficient catalysts.
To ensure that enzymes remain unchanged after the product is made, they have specific active sites where the substrates bind and reactions occur. The active site's chemical environment and amino acid residues within the active site contribute to the enzyme-substrate specificity and catalytic activity. This allows the enzyme to selectively bind and convert specific substrates into products without being modified or consumed in the process.