“Proteins are polymers of amino acid covalently linked through peptide bonds into a chain. Within and outside cells, proteins serve a myriad of functions, including structural roles (cytoskeleton), as catalysts (enzymes), transporter to ferry ions and molecules across membranes, and hormones.” (http://www.vivo.colostate.edu/hbooks/genetics/biotech/basics/prostruct.html)
Proteins are polymers of amino acids joined together by peptide bonds. There are 20 different amino acids that make up essentially all proteins on earth. Each of these amino acids has a fundamental design composed of a central carbon (also called the alpha carbon) bonded to; a hydrogen, a carboxyl group, an amino group and a unique side chain or R-group. The characteristic the distinguishes one amino acid from another is its unique side chain, and it is the side chain that dictates an amino acids chemical properties. The unique side chains confer unique chemical properties on amino acids, and dictate how each amino acid interacts with the others in protein. Amino acids can be classified as being “hydrophobic versus hydrophilic and uncharged versus”- Biology AS Level for AQA page 36. Ultimately, the three dimensional side chains. Some aspects of protein structure can be deducted by examining the properties of clusters of amino acids. For example- “a computer program that plots the hydrophobicity profile is often used to predict membrane-spanning regions of a protein or regions that are likely to be immunogenic.” (http://www.chemguide.co.uk/organicprops/aminoacids/proteinstruct.html)
Amino acids are covalently bonded together in chains by peptide bonds. If the chain length is short (for example less than 30 amino acids) it is called a peptide; longer chains are called polypeptides or proteins. Peptide bonds are formed between the carboxyl group of one amino acid and the amino group of the next amino acid. Peptide bond formation occurs in a condensation reaction involving loss of a molecule of water.
There are different levels of protein