The 20 amino acids

AAlaAlanine Small Hydrophobic Helix: ++ Strand: – Turn: – – Mutate to Ala if you have to mutate but have no clue to which residue

CCysCysteine Small Hydrophobic Sulfur containing Helix: – Strand: + Turn: + The SH-group is very reactive: Can make Cys-Cys bridges Can bind metal ions (especially Zn and Cu)

DAspAspartate Intermediately large Hydrophilic Negatively charged Helix: 0 (++ at N-terminus) Strands: – – Turn: ++ Often in active sites Can bind ions (mainly calcium)

EGluGlutamate Large Hydrophilic Negatively charged Helix: ++ Strand: 0 Turn: –

FPhe Phenylalanine Large Hydrophobic Aromatic Helix: 0 Strand: ++ Turn: – –

GGlyGlycine Smallest residue No side chain Hydrophobicity undetermined Very flexible Star of the turn Helix: – – Strand: – Turn: ++

HHisHistidine Large Hydrophilic Charge (depending on the environment): Positive Neutral or Negative No secondary structure preference Often in active sites Can bind metal ions (mainly Zn, Ni, Cu)

IIleIsoleucine Intermediately large Hydrophobic Helix: 0 Strand: ++ Turn: – –

KLysLysine Large Hydrophilic Positively charged Helix: ++ Strand: – Turn: 0 Long, flexible side chain

LLeuLeucine Intermediately large Hydrophobic Helix: ++ Strand: + Turn: – –

MMetMethionine Large Hydrophobic Sulfur containing Helix: ++ Strand: 0 Turn: – – Non-reactive sulfur which can bind metal ions Often the first residue of the sequence

Intermediately large Hydrophilic Helix: – – Strand: 0 Turn: ++ Can bind ions (Ca) but not as well as its isosteric partner Asp NAsnAsparagine

PProProline Small Hydrophobic Helix: – – (except at the first position) Strand: – – Turn: ++ Imino acid No backbone proton Pre-bend for turns

QGlnGlutamine Large Hydrophilic Helix: + Strand: 0 Turn: 0 Isosteric with Glu

Large Hydrophilic Positively charged No secondary structure preference Contains a rigid guanidinium group RArgArginine

SSerSerine Small Intermediate hydrophobicity Alcoholic Helix: – Strand: – Turn: ++ Often in active sites (with Asp and His) Can bind calcium

TThrThreonine Small Intermediate hydrophobicity Alcoholic Helix: 0 Strand: + Turn: 0 Can bind calcium

VValValine Small Hydrophobic Helix: 0 Strand: ++ Turn: – – Isosteric with Thr

WTrpTryptophan Largest residue Hydrophobic Aromatic Helix: 0 Strand: ++ Turn: 0 Most conserved residue

YTyrTyrosine Large Intermediate hydrophobicity Aromatic Alcoholic Helix: – Strand: ++ Turn: 0