• Gly=G
• smallest
• no potential for H-bonding
• not reactive
• doesn't stabilize alpha-helices

[image]

• Alanine=Ala=A; +1.8[image]
• a bit bigger than G so stabilize a-helices better

• Valine = Val = V; +4.2
• (v-shaped)
• [image]

• transfer from acetone to water
• (+)
• positive = positive deltaG transfer
• hydrophobic

• (-)
• hydrophilic

• G, A, V, L, I, P

• Leucine = Leu = L; +3.8
• same properties as valine but longer[image]

• Ile = I; +4.5
• isomer L
• long chain aliphatic group
• most hydrophobic[image]

• Pro = P; -1.6
• slightly hydrophilic
• only cyclic amino acid
• constrains rotation @ N-C(alpha) bond --> helix breaker[image]

• S, T, C, M, N, Q

• Ser = S; -0.8
• good hydrogen bonder
• often reactive at active sites
• good eletrophile
• pKa not in physiological range (13)[image]

• Thr = T; -0.7
• don't need to worry as much about dissociation
• not as reactive as S
• but similar properties as S[image]

• Cys = C; +2.5
• not great H-bonder b/c of S not as EN
• serine analog
• pKa beyond phys range
• can be oxidized
• 2 cyc close to each other oxidize to get attachment
• (tie up protein chains)[image]

• Met = M; +1.9
• hydrophobic
• 1st a.a. in every portein as synthesized
• ATG = start codon -->Met[image]

• Asn = N; -3.5
• very hydrophilic
• good H-bonder[image]

• Gln = Q; -3.5
• same props as Asn but longer[image]

• F, Y, W

• Phe=F; +2.8
• very hydrophobic
• large
• strong UV absorber
• similar property throughout this group[image]

• Tyr=Y; -1.3
• strong H-bonder
• pKa too high to care about
• strong UV absorber[image]

• Trp = W; -0.9
• largest
• used the least (rarest)
• H-bonder
• UV absorber[image]

• K, R, H

• Lys = K; -3.9
• pKa = 10.5
• often in active sites
• good H-bonder
• potential for ionic bonds => because fully developed  charge on amino group
• salt bridge (ionic bond)[image]

• Arg = R; -4.5
• pKa = 12.5, hard to protonate
• most hydrophilic of all A.A.
• salt bridges
• H-bond etc...(same prop. as Basic group)[image]

• His = H; ( ? )
• cyclic
• pKa = 6.0 (around neautral PH = protonated)
• if around phys pH range = deprotonated
• buffer
• changes charge in different phys(?) pH
• important in active sites[image]

• D, E

• aspartate=asp=D; -3.5
• low pKa = 3.9[image]

• glutamate=glu=E; -3.5
• pKa = 4.2
• forms H-bonds
• salt bridges
• found in active sites 
• (same properties for asp)[image]

• @ neutral pH[image]