All About Protein

Protein is important to our body. it is used for growth and development of our body. protein contains in most of our body. hair, nails, DNA are just some of the examples of protein in our body.

inside of protein's structure, there is a long chain of a monomer called amino acid. now what is amino acid? amino acid is a molecule that contains of Nitrogen, Carbon, Oxygen, R group, and Hydroxyl group.

this picture is the general formula for amino acid. it looks complicated right? to simplyfy it, you have to separate the components for three different groups.

1. the first group is the amino group which located on the left. the amino group contains a single bond of N-H.
2. the second group is the carboxy group which located on the right side. the carboxyl group contains of COOH.
3. the third group is the R group. R is variable of 20 different types of amino acids.

to form a protein, an amino acid must be join the other amino acid. if two amino acids join together, it will form a peptide bond.

when two amino acids is joining together, the H and OH will separate themselves and forming H2O, or water. then, the C and N molecule will join together to form a peptide bond. when a peptide bond is formed, then we can call the structure protein because it is now a chain of amino acids.this process is called condensation reaction in protein.

this condensation reaction is a reversible reaction.to break a protein molecule into amino acid, we have to do the hydrolysis process so that H2O molecule once again will join the structure and separate the protein into two amino acids.

when there are only two amino acids, the protein formed is called dipeptide. when there are more than two amino acids, the protein formed is called polypeptide.polypeptide protein's structure is more complicated than dipeptide due to many amino acids presence in polypeptide structure while in dipeptide, there are only 2 amino acids in the structure.

there are 4 different structures of protein.the structures called primary, secondary, tertiary, and quatenary.

the primary structure is the simplest struture among all of the structures. the shape for primary structure is a long chain containing many amino acids and peptide bonds. the features of this structure is they have a covalent bonds on its structure.

for the secondary structure, it has two different based structures, the alpha-helix, and beta-sheets

both alpha-helix and beta-sheets are held by hydogen bonds. these hydrogen bonds work as the "directional interactions" for the protein folding to form alpha and beta. hydrogen bond is formed when H atom have a covalent bond with electronegative atom (donor) and another electronegative atom (acceptor)

the tertiary structure is way more complicated than the other two structures.

basically, tertiary bonds is just a complex structure that contains many polypeptides. if you notice in the picture, there is a term "hydrophobic interaction". the hydrophobic interaction is the relation between water (H2O) and carbons that do not interact with water molecules.

the other features in tertiary structure beside the hydrophobic interaction are hydrogen bond (as we know before), ionic bond, and disulfide bridge

disulfide bridge is a bond that form by S-S molecules. this disulfide bond is very important to the shape of the tertiary structure.

the last structure, and the most complicated one, is the quartenary structure.

the quaternary structure is consist of a several tertiary structure combined. just like the tertiary structure, quaternary structure have so many bonds inside such as hydrigen bonding, disulfide bridge, ionic bond, and hydrophobic interaction.

the example of this quaternary structure is human insulin. insulin have two protein chains consist of 51 chains of amino acids.insulin is used for balancing the amount of sugar insinde your body (homeostasis reaction).

references:

http://elmhurst.edu/~chm/vchembook/567quatprotein.html

http://www.els.net/WileyCDA/ElsArticle/refId-a0003011.html

http://www.biologyguide.net/cells/large_molecules.htm

http://www.chemguide.co.uk/organicprops/aminoacids/proteinstruct.html

http://chemwiki.ucdavis.edu/Physical_Chemistry/Physical_Properties_of_Matter/Atomic_and_Molecular_Properties/Intermolecular_Forces/Hydrophobic_interactions

http://academic.brooklyn.cuny.edu/biology/bio4fv/page/disulfi.htm