1. COO - R group Amino group Carboxylic group L -Form Amino Acid Structure  H = Glycine CH 3 = Alanine H N 3 + H Juang RH (2004) BCbasics

2. Mirror Images of Amino Acid   Mirror image Same chemical properties Stereo isomers Juang RH (2004) BCbasics

3. LeuL -C-C-CONH 2 -C-CONH 2 -C-COOH-C-C-COOH -H -CH 3 -C-OH-C-SH -C-C-S-C PPro -C-C C N N + -C-C-C-C-NH 3 + -C- -C- -OH -C- N South line Circular line Central line Nan-Kan line Chung-San line Northwest line Aliphatic Amide Acidic Imino, Circular Basic SulfurHydroxy Aromatic -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 GlnQAsnN AspDGluE PheF ArgR LysK HisH GlyG A AAlaVValI Ile Y Tyr SerS ThrTMetM CysC Amino Acid Subway Map TrpW Non-polar Polar Juang RH (2004) BCbasics This is NOT a metabolic pathway

4. POLAR NON- POLAR TyrHis Gly AcidicNeutralBasic Asp Glu Gln Cys Asn Ser Thr Lys Arg Ala Val Ile Leu Met Phe Trp Pro Classification of Amino Acids by Polarity Polar or non-polar, it is the bases of the amino acid properties. Juang RH (2003) Biochemistry

5. NH 2 COOH 1 NH2NH2 2 NH 2 C NCOOH O H 21 Amino acids are connected head to tail Formation of Peptide Bonds by Dehydration Dehydration -H 2 O Carbodiimide Juang RH (2004) BCbasics

6. Peptide Bond Is Rigid and Planar H C C N C O Juang RH (2004) BCbasics