Amino Acid is any of the organic compounds in which one (or more ) amino group
(-NH2) and one (or more ) carboxylic acid group (-COOH) are both present
with general formula R-CH(NH2)COOH
containing carbon, hydrogen, oxygen, nitrogen, and in certain cases sulfur atoms. Two groups attached to the same carbon
(called the alpha-carbon atom at the end of the compound) are polymerized to form
peptides and proteins. The amine group is protonated to form -NH3+ at low pH. The
carboxylic acid group is deprotonated to form -CO2- at high pH. The carbon atom
in the carboxyl group of one amino acid binds covalently to the nitrogen atom in
the amino group of another amino acid to form a peptide bond with the release of
a water molecule. Proteins are synthesized through the covalent chemical
polypeptide bonds. The sequence of these amino acids in the protein polypeptides
determines the shape, properties, and hence biological role of the protein that
function as chemical messengers and as intermediates in metabolism. Proteins are
composed of various proportions of about 20 commonly occurring amino acids.
Plants or other biological systems can synthesize amino acids from simple
inorganic compounds, but animals rely on adequate supplies in their diet. More
than 100 common amino acids occur in plants or in other microorganic systems.
The 20 amino acids commonly found in animals are Alanine, Arginine, Asparagine,
Aspartic Acid, Cysteine, Glutamic Acid, Glutamine, Glycine, Histidine,
Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Proline, Serine,
Threonine, Tryptophan, Tyrosine, and Valine. Many of the amino acids can be
synthesized in the human or animal body from other cellular metabolites when needed (called Non-essential Amino
Acids). Animals are not able to synthesize some amino acids necessary in
metabolism in sufficient quantities. It must therefore be present in the diet
(called Essential Amino Acids). In man, these essential amino acids are
Arginine, Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine,
Threonine, Tryptophan and Valine. Valine, Isoleucine and leucine are all branched-chain
amino acids, which can be burned for fuel in the cells to promotes muscle
recovery when in balance with each other most effective. Only the
L-stereoisomers appear in mammalian protein. They play a role in wound healing
and the growth of new tissue. These branched amino-acids are needed to increase
the bio-availability of complex carbohydrate intake and are absorbed by the
muscle cells for anabolic muscle building activity. |