Amino Acids

As we all know, protein is one of the six essential nutrients that human body consumes on the daily bases. Most of the time, proteins are used to build our muscles or the cell membrane. Amino acids, which we are going to talk about in the post, play an important role in building up blocks of proteins. They also help our body go under metabolism.

  • Amino acid is a compound that contains a basic amino group (-NH2), an acidic carboxyl group (-COOH), and an organic R group (or side chain) that is unique to each amino acid in the same molecule. (Also defined as: a organic compound that is made up of C, H, N, O elements)
  • There are different amino acids because there could be different side chains attached to the central carbon, making the structure of one amino acid unique from others.
  • The amino group (-NH2), carboxyl group (-COOH), the Hydrogen atom(H), and the side chain (R) are all covalently bonded to the central carbon atom (alpha carbon also considered "chiral carbon").
    • Chiral carbon is a carbon that is bonded to four different groups.
      • Chirality refers to optical activity which refers to optical isomers that we are going to talk about later.
  • RECALL: The names "amino group" and "carboxyl group" are functional groups that we used to identify compound types in chapter 23 p. 726 of our chemistry book.
  • As discussed in chapter 23 of the chemistry book , the side chain R can be any "C bonded with H" structure. It can be a very long chain of C and H. As long as it only contains C and H, it is considered a side chain.
  • When used by scientists and chemists, the term "amino acid" is usually referring to the 20 common amino acids that can be found in living organisms.
  • 20 common amino acids:
  • There are three types of amino acids. They are essential amino acids, nonessential amino acids, and conditional amino acids.
    • Essential amino acids cannot be made by human body. They have to be ingested from food (most of the time: meat). There are arguments going on about how many essential amino acids there are.
      • The nine essential amino acids that most of the scientists admited are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
    • Nonessential amino acids can be produced by our body.
      • Some of the examples of nonessential amino acids are: alanine, asparagine, aspartic acid, and glutamic acid.
    • Conditional amino acids are not essential unless the body is under stress or sickness.
      • Examples: arginine, cysteine, glutamine, tyrosine, glycine, ornithine, proline, and serine.
  • Amino acids can be optical isomers. Some of the amino acids could have the same molecular formula, but they will have different properties if the molecular structures vary.
    • RECALL: optical isomers - isomers that are mirror images of each other.
    • 220px-D+L-Alanine.gif(the two enantiomers of alanine, D-Alanine and L-Alanine)
    • L-amino acids: amino group is on the left side.
    • D-amino acids: amino group is on the right side. ("D" stands for "dextro" which means "right" in Latin)
    • L- and D- amino acids are mirror images of each other.
    • The L-amino acids are the only kind of amino acids found in human body.
More information over amino acids:
  • a video from khan academy: amino acid
    • Beginning-3:22: How amino acids help metabolism and where they fit in the big view of biochemistry
    • 3:22-end: The structure of amino acids

Polymers of Amino Acids

Peptides - any combination of amino acids in which the amino group of one amino acid is united with the carboxyl group of another amino acid
  • The H of one amino acid's amino group bonds with the OH of the other amino acid's carboxylic group to form a water molecule. Then the N of that amino acid's amino group will form an amide bond with the C of the other amino acid's carboxylic group which is called a peptide bond.
  • The C and N must from the central amino group and central carboxylic group which are the groups bonded to the cental carbon. The bonding of C in the side chains wouldn't count.
Proteins - a peptide with more than about 100 amino acids
  • It is possible to keep adding amino acids to a peptide group to form a very long chain. That is the basic idea of protein.
  • The different oder that the amino acids are put together and the type of amino acids would cause the protein to vary.


SUMER H. -- What would you consider to be a real world application of amino acids and is there anything specific you think that could be produced or found through continued research into amino acids?
Alex X. - As I said at the beginning, amino acid is good for our body. It is the building block of proteins. Even if we are not sick, it is always good for our body to ingest some amino acids. There are particular pills made for that. And amino acids can also be used to treat disease. Here is an example that I found online: tyrosine, which is one of the amino acids, can be used to treat Alzhemer's disease.