The key difference between phenylalanine and tyrosine is that phenylalanine is an essential amino acid which cannot be made in our body and must be included into the diet while tyrosine is a nonessential amino acid which can be formed from the phenylalanine in our body.
There are twenty different amino acids. Some amino acids are essential amino acids, meaning that they are not formed in our body. In contrast, there are some nonessential amino acids which can be formed inside our body. Phenylalanine is an essential amino acid which is a precursor for tyrosine while tyrosine is a nonessential amino acid. Both phenylalanine and tyrosine are aromatic family amino acids. They are important for the production of various different substances in our body.
CONTENTS
1. Overview and Key Difference
2. What is Phenylalanine
3. What is Tyrosine
4. Similarities Between Phenylalanine and Tyrosine
5. Side by Side Comparison – Phenylalanine vs Tyrosine in Tabular Form
6. Summary
What is Phenylalanine?
Phenylalanine is an essential amino acid which cannot be produced in our body. Therefore, it should be included in our diet. Breast milk, meat, poultry, fish, cottage cheese, lentils, peanuts, and sesame seeds are rich in phenylalanine. Phenylalanine is a precursor for tyrosine, which is a nonessential amino acid. Moreover, phenylalanine is a precursor for catecholamines, including tyramine, dopamine, epinephrine, and norepinephrine.
Figure 01: Phenylalanine
Structurally, phenylalanine is closely related to dopamine, epinephrine and tyrosine. The chemical formula of phenylalanine is C9H11NO2 while the molecular mass is165.19 g/mol. The codons UUU and UUC in mRNA sequence code for this amino acid.
What is Tyrosine?
Tyrosine is a nonessential amino acid and a hydrophobic amino acid. The codons UAC and UAU in mRNA sequence code for tyrosine. The chemical formula of tyrosine is C9H11NO3 while the molecular mass is 181.191 g·mol−1. Our body can synthesize tyrosine from phenylalanine. Therefore, it is necessary to have an initial amount of phenylalanine in order to produce tyrosine. The enzyme phenylalanine hydroxylase catalyzes the hydroxylation of phenylalanine into tyrosine. This enzyme is expressed in the liver and kidney.
Figure 02: Tyrosine
Tyrosine metabolizes into important substance in our body such as epinephrine, norepinephrine, melanin, tissue pigments and estrogen. However, the conversion of tyrosine into other substances requires the presence of folic acid, niacin, vitamin C, and copper, etc. Moreover, tyrosine is an antidepressant amino acid. Hence, it is useful for decreasing anxiety and boosting energy. Furthermore, tyrosine has an antioxidant property. Therefore, it is useful in preventing cell and tissue damage by free radicals. Tyrosine is also needed for metabolism.
What are the Similarities Between Phenylalanine and Tyrosine?
- Both phenylalanine and tyrosine are indispensable amino acids.
- They are an aromatic family of amino acids.
- Phenylalanine is converted into tyrosine by phenylalanine hydroxylase.
- Both have antidepressant effects and are useful in the treatment of depression and anxiety.
- Both can deliver similar strong mood-lifting effects.
- Moreover, they are useful as markers of protein metabolism.
What is the Difference Between Phenylalanine and Tyrosine?
Phenylalanine is an essential amino acid which should be included in our diet while tyrosine is a nonessential amino acid which is synthesized from phenylalanine in our body. So, this is the key difference between phenylalanine and tyrosine. The chemical formula of phenylalanine is C9H11NO2 while the chemical formula of tyrosine is C9H11NO3.
Moreover, codons UUU and UUC code for the amino acid phenylalanine while codons UAC and UAU code for the tyrosine.
Below is a more detailed comparison of the difference between phenylalanine and tyrosine.
Summary – Phenylalanine vs Tyrosine
Phenylalanine is an essential amino acid which is the precursor for tyrosine. Tyrosine is a nonessential amino acid which can be formed in our body. So, this is the key difference between phenylalanine and tyrosine. Structurally, they are closely related and make up the aromatic family of amino acids. Moreover, they are important for the production of a variety of compounds in our body.
Reference:
1. “Phenylalanine – An Overview | Sciencedirect Topics”. Sciencedirect.Com, 2020, Available here.
2. “Tyrosine”. En.Wikipedia.Org, 2020, Available here.
Image Courtesy:
1. “L-Phenylalanin – L-Phenylalanine” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia
2. “L-Tyrosin – L-Tyrosine” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia