AMINO ACIDS

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AMINO ACIDS PROTEINS
R W Grime Ripon Grammar School
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AMINO ACIDS
amine group
carboxylic acid group
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glycine
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alanine
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valine
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serine
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aspartic acid
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• amino acids are chiral (except glycine where R
  H)
• only one enantiomer occurs usually

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Neutral pH
High pH (alkaline)
Low pH (acidic)
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Draw the structure of the amino acid at the pH
shown.
pH 12
pH 2
pH 13
pH 4
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Draw the structure of the amino acid at the pH
shown.
pH 12
pH 2
pH 13
pH 4
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Joining amino acids together to make polypeptides
and proteins
Condensation reaction molecules join and water
is eliminated
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Breaking down polypeptides and proteins into
amino acids
Needs acid or enzyme
Hydrolysis reaction reaction with water in which
O-H bond breaks
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• Primary structure
• This is the sequence of amino acid units in the
  chain.
• Secondary structure
• The chain is often arranged in a helix (coil)
  this is the secondary structure.
• The helix is held together by H-bonds between
  CO..H-N in adjacent spirals of the coil.
• There are a large number of H-bonds in the helix
  giving a stable structure.
• Proteins can have other less common secondary
  structures, but they still have H-bonding.

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• Teriary structure
• The helix is folded into a characteristic 3-D
  shape known as the tertiary structure.
• This is held together by various bonds between R
  groups in the amino acid groups