The Ways In Which Four Amino Acids, Histidine, N

Abstract:
An experiment in which four amino acids, histidine, lysine, glutamine, and glutamic acid, are identified based on their titration behavior. Solutions of each unknown amino acid are made and the change in pH upon adding small amounts of NaOH aliquots of a strong base are monitored. The amino acids are identified using the information represented by the titration curves. The titration curves include the following information: isoelectric points, pKas, buffering regions and the structures of the amino acids. The results of the experiment were that the unknown that was labeled A was concluded to be lysine, unknown B was figured to be glutamic acid, unknown C was concluded to be histidine, and unknown D was glutamine.
Introduction:
The protonation states of amino acids are important for understanding enzymatic catalysis, pH changes, and the intermolecular interactions which stabilize the tertiary and quaternary structure of proteins (1). As the building blocks of proteins, amino acids are the key role of structure, function, and inactions with other molecules. Proteins alone are involved in almost every physiological event in a cell. Chemists use titration curves to determine a concentration of a substance of a solution which could be an acid or a base. A titration curve of an amino acid is a plot of the pH of a weak acid against the degree of neutralization of the acid by a standard base. Lysine, glutamine, glutamic acid, and histidine were analyzed in this experiment. These amino acids were selected because they have quite similar molar masses (155.1 for histidine, 146.2 for lysine, 146.1 for glutamine and 147.1 for glutamic acid) so that equal masses of the amino acids will make solutions of approximately the same concentration (1). This makes it easier to identify the amino acids correctly by using the titrations