In this experiment paper chromatography was used in order to identify two unknown amino acids using eight known amino ones. The two unknown ones were identified by comparing the distance they travelled up the chromatography paper and their Rf values to the corresponding values of the other eight known amino acids. The unknown amino acids identified were Glycine and Methionine.
Introduction Proteins in cells are important in many ways. There are different types of proteins such as contractile proteins, enzymes, hormonal proteins, structural proteins and transport proteins. They are vital to regular cell functioning. Proteins are made up of amino acids that are joined together by peptide bonds. When fewer than 50 amino acids are joined together, a polypeptide is formed. All proteins have two groups in common. They have a carboxylic group and an amino group. There are 20 types of amino acids that bond together in different combinations to perform different functions. The primary structure of proteins is the order and number of amino acids. Secondary, tertiary and quarternary structures are formed from chains of peptides that are folded into sheets, ribbons and coils so that they form a 3D shape and are more stable. Different weights of amino acid make them differ in polarity. This characteristic enables the separation of proteins by polarity using chromatography. Paper chromatography is an example of a chromatography technique called absorption chromatography. The paper is the adsorbent, which will bind the components of the mixture. The substance will be “spotted” onto the chromatography paper and put into a beaker filled with solvent. The solvent will then flow through the paper. The solvent chosen depends highly on its polarity as this will be the characteristic that will separate the different substances. Petroleum, ether, hexanes, cyclohexanes and toluene are some examples of solvents with different polarities as well as increasing polarities.