Re: what is the relationship between nitrogen and protein in the human body?

Hi Tom,

The four most abundant elements in all living things are hydrogen, oxygen, carbon and nitrogen. Nitrogen is an essential element of both proteins and nucleic acids (DNA and RNA). Both proteins and nucleic acids are polymers built up from relatively simple units. In the case of nucleic acids, these basic units are known as nucleotides, while in the case of proteins, the basic units are known as amino acids.

Nucleotides are complex structures in and of themselves; each is composed of a sugar (either a ribose or a deoxy-ribose) and a nitrogenous base. The nitrogenous base is either a 1 or 2 ring structure, and several of the atoms in these rings are nitrogen atoms.

Amino acids are simpler in structure than nucleotides. Each amino acid has a central carbon atom, with a carboxyl group (-COOH) on one end, and an amine group (-NH3) on the other end. You will notice that the amine group contains a nitrogen atom. In addition, most amino acids have a complex side chain attached to the central carbon, and some of these side chains can contain nitrogen atoms as well.

So, all proteins are polymers of 100s to 1000s of amino acids that contain at least 1 nitrogen atom each. Similarly, all DNA and RNA molecules are polymers of up to a few hundred million nucleotides that each contain multiple nitrogens atoms.

In addition, nitrogen is often an important part of many enzymatic cofactors; for example, the porphyrin ring found in the heme co-factor of hemoglobin (as well as in chlorophyll) contains several nitrogen atoms. Glutathione is a non-protein tri-peptide co-factor comprised by three amino acids. When amino acids are broken down, the amine groups are incorporated into urea, which is excreted in urine. Finally, the word vitamin is derived from the term "vital amine", the name given to vitamin B1 by Dr. Casimir Funk in 1911. A deficiency of this nitrogen-containing compound results in the condition known as Beriberi.

So, I hope you can see that nitrogen is an essential component of proteins and nucleic acids, and nitrogenous compounds are crucial to our metabolisms. For more information, I suggest searching our archives for answers containing the words protein and nitrogen, and consulting a college-level biochemistry text. I prefer Biochemistry, by L. Stryer.