Role of Amino Acids in the Human Body

Amino acids are a very important class of chemical compounds that are 20 in number.  Each amino acid is composed of a carboxyl group and an amino group  in which both are attached to a CH group.  The difference between each and each amino acid is in the length and type of chemical group that is attached to the CH group also. 

This difference will also dictate if the amino acid will be polar or nonpolar.  Alternatively it will dictate if the amino acid will be hydrophobic or hydrophilic based on the type of group that is attached to the CH group. 

Amino acids are an extremely important group of molecules due to its being the building block of all proteins in the body which include the important class of proteins the enzymes.  Due to their importance as building block for protein their supply to the body is important.  Fortunately the body is able to synthesize part of the 20 amino acids from nitrogenous compounds in the body. 

This part of the 20 amino acids and which the body is able to synthesize or make is called non-essential amino acids.  Other amino acids that the body cannot synthesize or make must be given in the diet in the form of tablets.  These are called essential amino acids. 

Amino acids exist in the body in zwitterion structure due to the existence of the amino and carboxyl groups in its structure.  Amino acids are capable of forming chemical bonds between each other.  The amino group of one amino acids can form a peptide bond with the carboxyl part of another amino acid. 

Proteins are polymers of amino acids and which are connected via peptide bonds.  Amino acids are metabolized in the liver to the toxic compound of ammonia by a deamination process of the amino group in the amino acid.  Ammonia is then converted to the less toxic compound of urea which in then secreted in the urine out of the body. 

Amino acids in addition to their importance as building block for all proteins have other functions or are metabolized to other important molcules in the body.  Amino acids can function as neurotransmitters in the nervous system.  For example, the teo amino acids aspartic acid and glutamic acid are strong excitatory neurotransmitters in the central nervous system. 

90% of the excitatory nerve cells in the central nervous system and 50% of them in the brain communicate through the amino acid glutamic acid.  Excess of glutamic acid in the body can cause excitatory toxicity in which nerve damage occurs.  A disease which is characterized by by excessive function of the glutamic acid is called amyotrophic lateral sclerosis.  A drug which is called riluzole works by inhibiting the action of the glutamic acid in the nervous system. 

A non-typical amino acid and which is usually not incorporated into protein structure is called gama-amino butyric acid or GABA.  This amino acid is the main inhibitory neurotransmitter in the nervous system. Its analogues are prescribed as anti-anxiety drugs and against panic attacks.   In addition to GABA, the amino acid glycine is is also another inhibitory amino acid in the nervous system.   

In addition to the amino acids themselves modifications and decarboxylations of certain amino acids can create neurotransmitters such as the catecholamines, which are important physiologically to the proper function of the nervous system.  These neurotransmitters are called catecholamines.  They are all synthesized from the amino acid tyrosine by enzymatic modification and by decarboxylation process. 

Another important neurotransmitter in the nervous system is called serotonin.  It is a derivative of the amino acid tryptophan.  It is an important neurotransmitter due to its important physiological function in the etiology of the psychiatric condition of depression.  It was found that excessive amount of serotonin in the blood will eliminate the depression symptoms.  In addition it was found that people who have or suffer from depression have low level of serotonin in their blood.