QUALITATIVE ANALYSIS OF AMINO ACIDS AND PROTEINS

QUALITATIVE ANALYSIS OF AMINO ACIDS AND PROTEINS

Background :
Amino acids are molecules containing an amine group, a carboxylic acid group and a
side chain that varies betwen different amino acids. Amino acids of the general formula
RCH(NH2)COOH are amphoteric, behaving as amines in some reactions and as
carboxylic acids in others. At a certain pH known as the isoelectric point an amino acid
has no overall charge, since the number of protonated ammonium groups (positive
charges) and deprotonated carboxylate groups (negative charges) are equal. Since the
amino acids at their isoelectric points have both negative and positive charges, they are
known as zwitterions.
Amino acids are critical to life. They have particularly important functions like being the
building blocks of proteins and being the intermediates in metabolism.
Amino acids are generally classified by the properties of their side chain into four
groups. The side chain can make an amino acid a weak acid or a weak base, and a
hydrophile if the side chain is polar or a hydrophobe if it is nonpolar.
Proteins (also known as polypeptides) are organic compounds made of amino acids
arranged in a linear chain. The amino acids in a polymer are joined together by the
peptide bonds between the carboxyl and the amino groups of adjacent amino acid
residues.
Like other biological macromolecules such as polysaccharides and nucleic acids,
proteins are essential parts of organisms and participate in virtually every process
within cells