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α-Amino Acids
generic structure of an alpha-amino acid
The generic structure of an α-amino acid
QUESTION Which common amino acid doesn't quite fit the generic formula ? ANSWER

Amino acids with non-polar side chains. The hydrophobic side chains are chemically unreactive and tend to aggregate rather than be exposed to the aqueous environment, so they tend to found on the interior of proteins.  Hydrophobic means "water hating" - remember "oil and water don't mix" and "like dissolves like" - this is because non-polar hydrocarbons do not interact with polar water molecules in an energetically favourable way - they would rather interact with another non-polar hydrocarbon molecule : this it the hydrophobic effect - the aggregation of non-polar systems in an aqueous environment.
(see also "micelles")
 

Amino acid
Abbreviations
Structural Formula
3D-representation
Glycine
Gly (G)
glycine
Alanine
Ala (A)
Valine
Val (V)
Leucine
Leu (L)
Isoleucine
Ile (I)
Methionine
Met (M)
Proline
Pro (P)
Phenylalanine
Phe (F)
Tryptophan
Trp (W)

 

Amino acids with polar side chains.  These are side chains can be involved in hydrogen bonding interactions. Cysteine is important because of its ability to form disulfide bonds.

Amino acid
Abbreviations
Structural Formula
3D-representation
Asparagine
Asn (N)
Glutamine
Gln (Q)
Serine
Ser (S)
Threonine
Thr (T)
Tyrosine
Tyr (Y)
Cysteine
Cys (C)

 

Amino acids with acidic side chains. These carboxylate group will be -ve at physiological pH.   Often involved at the active sites of enzymes, in hydrogen bonding interactions and in acid/base type reactivity.
 

Amino acid
Abbreviations
Structural Formula
3D-representation
Aspartic acid
Asp (D)
Glutamic acid
Glu (E)

 

Amino acids with basic side chains.  Often involved at the active sites of enzymes, in hydrogen bonding interactions and in acid/base type reactivity (e.g. histidine)

Amino acid
Abbreviations
Structural Formula
3D-representation
Lysine
Lys (K)
Arginine
Arg (R)
Histidine
His (H)

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© Dr. Ian Hunt, Department of Chemistry, University of Calgary