1)Amino acids 1. Chiral, only L-isomers exist in living world. 2. Zwitterions; Functional groups give the diversity and versatility, 3. G is achiral; P has a cyclic alpha carbon; A, V, L, I, M (hydrophobic); M, C (sulfur-containing); S, T, C, M, N, Q (polar); H, K, R (basic); D, E (acidic); F, Y, H, W (aromatic). 2)Protein structure and function 1. Peptide bond: conformation, α-helix, β-sheet, random coil. 2. Structure: 1˚, 2˚, 3˚ and 4˚; motif and domain. 3. Posttranslational modification 4. Protein folding 5. Protein function Lecture 3 Amino acids, peptides and proteins