In 1953, Harold Urey and also Stanley Miller lugged out an exceptional experiment in which they developed "molecules of life" native a mixture that gases that they proposed exist in a primordial earth. The experiment simulated what would take place when lightning strikes provided energy because that chemical reaction in the atmosphere and also suggested a hypothesis for just how life might have occurred on our planet. Amino acids to be the vital molecules that created in this experiment and supported this theory for the origin of life.

an amino mountain is a molecule that includes two functional groups , an amine and a carboxylic acid , as shown in number 1. In this illustration there is second group called the side chain, designated with an R. The variation viewed in naturally occurring amino mountain arises from differences in this next chain. The twenty naturally occurring molecules are listed in Table 1. In one aqueous equipment , this framework may adjust so the a proton indigenous the COOH move to the NH 2 and a zwitterion is formed. This structure relies on the pH the the solution. Most physiological systems loss into such a pH range so the zwitterion form of amino mountain is the many stable type in the person body.

The stereochemistry the amino mountain is also an important concept. The carbon atom marked α in figure 1 is chiral, so an amino acid can be one of two enantiomers. Keep in mind that the structure shown in the illustration has actually the amine team on the right and also the carboxyl team in ~ the top. This construction is designated the l form, and also all naturally developing amino acids have actually this form.

Amino acids are categorized right into three groups based upon the nature the the side chain. Ripe of the amino acids have side chain that space nonpolar . Virtually 50 percent that the amino acids the are existing in proteins have actually nonpolar next chains. The 2nd category that amino acid contains six different molecules that have polar next chains. Finally, a team of five amino acids have side chain that space not just polar, yet charged.

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The crucial chemical characteristic of amino acids is the they attach together to kind proteins. Since the COOH functional group is one acid and the NH 2 functional team is a base, the two ends that amino acids deserve to readily react through each other. Protein synthetic is more complex than a straightforward acid-base neutralization, however consider what happens once two amino


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THE TWENTY usual AMINO ACIDS found IN proteins
name One-Letter Abbreviation Three-Letter Abbreviation
Glycine G Gly
Alanine A Ala
Valine V Val
Leucine l Leu
Isoleucine ns Ile
Methionine M Met
Phenylalanine F Phe
Proline ns pro
Serine S Ser
Threonine T Thr
Cysteine C Cys
Asparagine N Asn
Glutamine Q Gln
Tyrosine Y Tyr
Tryptophan W Trp
Aspartate D Asp
Glutamate E Glu
Histidine H His
Lysine K Lys
Arginine R Arg

acids react to type a peptide bond. The brand-new molecule, currently a dimer v two amino mountain residues still has one finish that is an acid and also another end that is a base, so it is evident that the process of developing a peptide bond with an additional amino acid could be repeated. If plenty of amino acids space strung together, the result is a organic polymer—a protein.


Barrett, G. C., and Elmore, D. T. (1998). Amino Acids and also Peptides. brand-new York: Cambridge college Press.

Cantor, C. R., and also Schimmel, P. R. (1980). Biophysical Chemistry, part I. san Francisco: W.H. Freeman.

Jones, J. (2002). Amino Acid and also Peptide Synthesis. Oxford: Oxford college Books.