1Figure 4-1General structural formula for α-amino acids.Figure 4-2Zwitterionic form of the a-amino acids that occur at physiological pH values.Voet and Voet, Biochemistry, chapter 4Voet and Voet, Biochemistry, chapter 4Figure 4-14 “CORN crib” mnemonic for the hand of L-α-amino acids.2Cox, Lehninger Principles in Biochemistry, chapter 5, figure 3Stereo-chemistry of α-alanineFigure 4-9 Greek lettering scheme used to identify the atoms in the glutamyl and lysyl R groups.Voet and Voet, Biochemistry, chapter 43Amino acids always carry charges at physiological pHFigure 4-6 Titration curve of glycine.Voet and Voet, Biochemistry, chapter 4Figure 4-7 Titration curves of the enzyme ribonuclease A at 25°C.Voet and Voet, Biochemistry, chapter 4The isoelectric point is the pH value where the net charge of a molecule is zero (equal number of positive and negative charges; e.g. +17/-17)4Figure 6-27 Two-dimensional (2D) gel electrophoresisVoet and Voet, Biochemistry, chapter 4The 20 naturally occurring L-α-amino acids in proteins5Cox, Lehninger Principles in Biochemistry, chapter 5Size Charge Solubility DistributionAmino acids sorted by size6Quality Amino acid Mol. weight (Dalton) 3 letter code 1 letter code Hydro phobicity* pKa non-polar Alanine 89.1 Ala A +1.8 Valine 117.15 Val V +4.2 Leucine 131.18 Leu L +3.8 Isoleucine 131.18 Ile I +4.5 Methionine 149.21 Met M +1.9 Phenylalanine 165.19 Phe F +2.8 Glycine 75.07 Gly G -0.4 Tryptophane 204.23 Trp W -0.9 Proline 151.13 Pro P -1.6 polar Serine 105.10 Ser S -0.8 Threonine 119.12 Thr T -0.7 Cysteine 121.16 Cys C +2.5 Asparagine 132.12 Asn N -3.5 Glutamine 128.10 Gln Q -3.5 Tyrosine 181.19 Tyr Y -1.3 charged Lysine 146.19 Lys K -3.9 10.54 Arginine 174.2 Arg R -4.5 12.48 Histidine 155.16 His H -3.2 6.04 Aspartate 133.11 Asp D -3.5 3.90 Glutamate 147.13 Glu E -3.5 4.07 Robert M. Clegg · Dept of Physics · University of Illinois Amino acids grouped by solubility considerationsSide chain derivatives found in proteins are the result of post-translational modifications.Other modifications are phosphorylation, acylation (fatty acids), glycosylation, ubiquitination.Fig. 4-hydroxypproline (C01015) and 5-hydroxylysine (C00598); from KEGG database Fig. 4-hydroxypproline (C01015) and 5-hydroxylysine (C00598); from KEGG database7Figure 4-22 Some uncommon amino acid residues that are components of certain proteins.Voet and Voet, Biochemistry, chapter 4Figure 4-23 Some biologically produced derivatives of “standard” amino acids and amino acids that are not components of proteins.Voet and Voet, Biochemistry, chapter
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