1.4.1 Amino acids are the building materials of proteins

1.4.2 Peptide bonds link successive amino acids to form proteins

Peptide 二肽

The primary structure of a protein is its amino acids to form sequence

1.4.3 Proteins are folded into 3 dimensional shapes that determine their functions

Secondary structure: α - helix and β - pleated sheet (eg. spider web).

Tertiary structure (3rd structure): disulfide bridges(bonds) 二硫键+hydrogen bonds

Quaternary structure (4th structure): forms when 2+ polypeptides subunits interact to form a protein.

1级-氨基酸 2级-氨基酸排列 3级-肽链 4级-多条肽链

Denaturation 蛋白质变性