QUALITATIVE ANALYSIS OF AMINO ACIDS AND PROTEINS

QUALITATIVE ANALYSIS OF AMINO ACIDS AND PROTEINS

Amino acids are molecules containing an amine group, a carboxylic acid group and a side chain that varies between 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. Proteins are important in:
- catalyzing biochemical reactions (enzymes)
- structural and mechanical functions (actin and myosin)
- cell signaling
- immune responses
- cell adhesion
- cell cycle .