A-level Chemistry/OCR (Salters)/Amino acids

α-Amino acids

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  The general structure of an α-amino acid. The α-carbon is displayed in orange, and the side chain is denoted by R. This style of diagram does not indicate whether the amino acid is an L or a D enantiomer.

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  The stereochemistry of an L-amino acid. All amino acids in nature are L-amino acids, except for bacterial cell walls and the odd w:en:cone snail or two.

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  A skeletal formula of a general α-amino acid. The α-carbon is displayed as an orange circle

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  The skeletal formula of a general L-α-amino acid, the enantiomeric form found in nature.

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  The skeletal formula of a general D-α-amino acid, the enantiomeric form not found in nature. D-amino acids can be synthesised artificially in a laboratory.

The twenty protein-forming amino acids

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  glycine
  Gly, G
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  L-alanine
  Ala, A
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  L-valine
  Val, V
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  L-leucine
  Leu, L
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  L-isoleucine
  Ile, I
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  L-phenylalanine
  Phe, F
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  L-proline
  Pro, P
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  L-tryptophan
  Trp, W
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  L-serine
  Ser, S
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  L-threonine
  Thr, T
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  L-cysteine
  Cys, C
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  L-methionine
  Met, M
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  L-aspartic acid
  Asp, D
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  L-glutamic acid
  Glu, E
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  L-asparagine
  Asn, N
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  L-glutamine
  Gln, Q
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  L-tyrosine
  Tyr, Y
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  L-histidine
  His, H
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  L-lysine
  Lys, K
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  L-arginine
  Arg, R

Reactions of amino acids

Amino acids can undergo condensation reactions, forming polypeptides.