Substitution preferences:
All protein types:
| Favoured | Ser ( 1) | |||||||
| Neutral | Val ( 0) | Cys ( 0) | Thr ( 0) | Gly ( 0) | ||||
| Disfavoured | Glu (-1) | Ile (-1) | Lys (-1) | Met (-1) | Leu (-1) | Pro (-1) | Gln (-1) | Arg (-1) |
| Asn (-2) | His (-2) | Phe (-2) | Asp (-2) | Tyr (-2) | Trp (-3) |
| Favoured | ||||||||
| Neutral | Cys ( 0) | Thr ( 0) | Glu ( 0) | Val ( 0) | Gly ( 0) | Ile ( 0) | Lys ( 0) | Met ( 0) |
| Leu ( 0) | Pro ( 0) | Gln ( 0) | Arg ( 0) | Ser ( 0) | ||||
| Disfavoured | Asp (-1) | Phe (-1) | His (-1) | Asn (-1) | Tyr (-1) | Trp (-2) |
| Favoured | ||||||||
| Neutral | Arg ( 0) | Ser ( 0) | Thr ( 0) | Glu ( 0) | Val ( 0) | Gly ( 0) | His ( 0) | Ile ( 0) |
| Lys ( 0) | Met ( 0) | Leu ( 0) | Asn ( 0) | Pro ( 0) | Gln ( 0) | |||
| Disfavoured | Phe (-1) | Tyr (-1) | Asp (-1) | Trp (-2) | Cys (-4) |
| Favoured | Ser ( 2) | Gly ( 1) | Thr ( 1) | |||||
| Neutral | Val ( 0) | Pro ( 0) | Ile ( 0) | Cys ( 0) | Asp ( 0) | Glu ( 0) | ||
| Disfavoured | Asn (-1) | Arg (-1) | Met (-1) | Phe (-2) | Lys (-2) | Leu (-2) | Gln (-2) | Tyr (-3) |
| His (-3) | Trp (-4) |
Role in structure: Alanine is arguably the most boring amino acid. It is not particularly hydrophobic and is non-polar. However, it contains a normal C-beta carbon, meaning that it is generally as hindered as other amino acids with respect to the conforomations that the backbone can adopt. For this reason, it is not surprising to see Alanine present in just about all non-critical protein contexts.
Role in function: The Alanine side chain is very non-reactive, and is thus rarely directly involved in protein function. However it can play a role in substrate recognition or specificity, particularly in interactions with other non-reactive atoms such as carbon.