Individuals with PKU have a mutation in the enzyme phenylalanine hydroxylase, which normally adds an alcohol group (OH) to the amino acid phenylalanine to form tyrosine as shown below.įigure 2.251 Phenylketonuria (PKU) results from a mutation in the enzyme phenylalanine hydroxylase 2,3 An example of a condition when an amino acid becomes essential is the disease phenylketonuria (PKU). Conditionally essential amino acids become essential for individuals in certain situations. Non-essential, or dispensable, amino acids can be made in our body, so we do not need to consume them. Web Linkĭiscovery of Threonine by William C. Rose at the University of Illinois discovered that threonine was essential by feeding different diets to graduate students at the university as described in the following link. As an example of how amino acids were determined to be essential, Dr. As a result these amino acids are known as essential, or indispensable, amino acids. Thus, it is essential that these are consumed in the diet. The body cannot synthesize nine amino acids. Table 2.251 Essential, conditionally essential, and nonessential amino acids 1 Essential The table below shows how the 20 amino acids are classified. These amino acids can be classified as essential, non-essential, or conditionally essential. There are 20 amino acids our body uses to synthesize proteins.
