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Amino Acids

Amino Acids. Devin Soderland. What Are Amino Acids?. Amino Acids a re molecules which contain: an amine group, a carboxylic acid group, and an R-grou p side-chain that is specific to each different amino acid. What Do Amino Acids Do?.

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Amino Acids

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  1. Amino Acids Devin Soderland

  2. What Are Amino Acids? Amino Acids are molecules which contain: an amine group, a carboxylic acid group, and an R-group side-chain that is specific to each different amino acid.

  3. What Do Amino Acids Do? • They are the “building blocks” of proteins – polypeptides and proteins are chains of amino acids held together by peptide bonds. • Amino acids are also important in nutrition and are commonly used in nutrition supplements, fertilizers, food technology and industry. • In industry, applications include the production of biodegradable plastics, drugs, and chiral catalysts. • Their primary importance is as the backbone of a wide variety of proteins, however.

  4. Essential and Standard Amino Acids • There are twenty amino acids which are naturally incorporated into polypeptides and are called “proteinogenic” or “standard” amino acids. • Nine of the standard amino acids are referred to as “essential” because they cannot be created in the human body and must be taken in as food. • The “essential amino acids” are: Histidine, Isoleucine, Leucine, Methionine, Tryptophan, Valine, Threonine,and Phenylalanine. • Amino acids have special common names, but a three letter abbreviation for the name is used most of the time. A second abbreviation, just a single letter, is used in long protein structures.

  5. Amino Acids and Chirals • Amino acids are enantiomers of each other – their structures are non-superposable mirror images, and nineteen of the twenty standard amino acids exist as L- or D-enantiomorphs. • L-amino acids are used exclusively for protein synthesis by all life on our planet. • The same nineteen out of the twenty standard amino acids have chiral centers as part of their structures. • Glycine is the only one of the twenty standard amino acids to not have a chiral center. This is because glycine’s R-group is a hydrogen.

  6. Formation Of Peptide Linkages • Also called “amide bonds”. • Are formed inside the ribosome of a cell. • Covalent bond. • Formed when the carboxyl group of one molecule reacts with the amino group of another molecule. • Reaction releases a molecule of water. • Dehydration synthesis/condensation reaction.

  7. Hydrolysis Of Peptide Linkages • Some covalent bonds, including peptide linkages, are broken by the addition of water. • Reverse reaction to the formation of peptide bonds. • The hydrogen from the water bonds to one monomer and the hydroxyl bonds to the other. • Produces two amino acid molecules.

  8. Non-Polar Amino Acids • This group is known as the “aliphatic” amino acids. • Aliphatic implies that the protein side chain contains only carbon or hydrogen atoms, and that the molecule is non-polar. • Hydrophobic; cannot hydrogen-bond with water. • Methionine is sometimes considered to be a part of the aliphatic amino acids, despite the sulfur.

  9. Sulfur-Containing Amino Acids • Generally considered to be non-polar. • Hydrophobic. • Cannot hydrogen-bond with water, due to the sulfur. • Cysteine ionizes to form the thiolate anion. • Methionine is one of the most hydrophobic amino acids and is almost always found on the interior of proteins.

  10. Polar Neutral Amino Acids • Neutrally-charged. • Hydrophilic; form hydrogen-bonds with water. • Serine and Threonine have very high hydroxyl groups, and are therefore usually considered to be non-ionizing. • Asparagine and Glutamine are generally found at the surface of a protein.

  11. Polar Basic Amino Acids • Polar and positively- charged. • Hydrophilic; easily form hydrogen-bonds with water.

  12. Polar Acidic Amino Acids • Negatively charged at physiological pH. • Both polar acidic amino acids have a second carboxyl group as part of their structure. • Hydrophilic; easily form hydrogen-bonds with water.

  13. Other Amino Acids • Aromatic amino acids: relatively nonpolar, and absorb UV light. Tyrosine is one of three hydroxyl-containing amino acids, and is the only aromatic amino acid with an ionized side-chain. • Proline is the only cyclical amino acid. It is nonpolar, can be inside or outside the protein, and shares many properties with the aliphatic group.

  14. Sources http://www.biology.arizona.edu/biochemistry/problem_sets/aa/aa.html http://www.elmhurst.edu/~chm/vchembook/561aminostructure.html http://www.sigmaaldrich.com/life-science/metabolomics/learning-center/amino-acid-reference-chart.html http://www.mcb.ucdavis.edu/courses/bis102/AAProp.html http://www.elmhurst.edu/~chm/vchembook/564peptide.html http://en.wikipedia.org/wiki/Peptide_bond http://www.sciencebugz.com/apbio/notes/Macromolecules.pdf http://people.umass.edu/bioch623/623/FirstSection/Papers/Pestko/nsp-protein-1-3.pdf http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Enantiomers.html http://quizlet.com/346531/hydrophobic-or-hydrophilic-aas-flash-cards/ http://www.russelllab.org/aas/aliphatic.html http://www.ann.com.au/MedSci/amino.htm

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