The document discusses the 20 standard amino acids that make up proteins. It covers the common structures of amino acids including the alpha carbon, acid group, amino group, and side chain. It also classifies the 20 amino acids based on the properties of their side chains, including nonpolar, aromatic, polar uncharged, negatively charged and positively charged groups. Key amino acid properties and the single letter abbreviations used to represent each one are also outlined.

6. Hydrophobic R groups Fig 3-5 Secondary amino (imino) group

8. Aromatic R groups Fig 3-5 Polarity: Tyr ~ Trp >> Phe Hydroxyl group

10. Polar, uncharged R groups Fig 3-5 Sulfhydryl group Hydroxyl group Amide group

12. Positively charged R groups Fig 3-5 At pH = 7.0 Imidazole group

13. Negatively charged R groups Fig 3-5 At pH = 7.0 = Aspartic acid = Glutamic acid

14. -C-C-CONH 2 -C-CONH 2 -C-COOH -C-C-COOH -H -CH 3 -C-OH -C-SH -C-C-S-C -C-C-C-C-NH 3 + 雙 和 線 環狀線 中央線 南 港 線 中 山 線 西 北 線 Aliphatic Amide Acidic Imino, Circular Basic Sulfur Hydroxy Aromatic 胺基酸地下鐵道圖 Juang RH (2004) BCbasics Leu L P Pro -C-C C N N + -C- -C- -OH -C- N -C-C-C-N-C-N N + = C -C-C-C C -C-C-C C C -C C C C HN C-COOH  -C-C OH Gln Q Asn N Asp D Glu E Phe F Arg R Lys K His H Gly G A A Ala V Val I Ile Y Tyr Ser S Thr T Met M Cys C Trp W Non-polar Polar

15. If only one amino acid (a.a.) begins with a certain letter, that letter is used Cys teine = Cys = C His tidine = His = H I so le ucine = Ile = I Met hionine = Met = M Ser ine = Ser = S Val ine = Val = V Key convention, p. 74

16. If more than one a.a. begins with a certain letter, that letter is assigned to the most commonly occurring one Ala nine = Ala = A Gly cine = Gly = G Leu cine = Leu = L Pro line = Pro = P Thr eonine = Thr = T

17. Phonetically suggestive Asp artic acid (“aspar D ic acid”) = Asp = D Phe nylalanine (“ F enylalanine”) = Phe = F Arg inine (“a R ginine”) = Arg = R Tyr osine (“t Y rosine”) = Tyr = Y Tr y p tophan ( double ring in the molecule) = Trp = W

18. A letter close to the initial is used As paragine (contains N ) = As n = N Glu tamic acid (near D) = Glu = E Gl utami n e (“Q-tamine”) = Gl n = Q Lys ine (near L) = Lys = K

19. THIS IS EASY … GREAT

21. Can you name these amino acids?