hydrophilic amino acids

hydrophobic amino acids

essential amino acids

non-essential amino acids

Ala, Arg, Asn, Asp, Cys, etc.

General physical properties

chemical properties

A polymer formed by covalently linking two or more amino acids through the condensation of α-amino and α-carboxyl groups with amide bonds (peptide bonds). It includes oligopeptides, polypeptides and proteins. Each amino acid unit that makes up a peptide is called an amino acid residue. The chain structure formed by amino acid residues connected by peptide bonds is called a peptide chain

Has partial double bond properties (40%). The bond length of peptide bond is 0.133nm, which is between C-N single bond (0.147nm) and C=N double bond (0.128nm).

The main basis for naming and classifying peptides is the number and composition of amino acid residues. Peptides can be classified according to the number of amino acid residues and are called peptides. For example, a peptide made of 2 amino acids is called a dipeptide, a peptide made of 3 amino acids is called a tripeptide, and so on. Generally, peptides composed of 2 to 10 amino acid residues are called oligopeptides, peptides composed of 11 to 50 amino acid residues are called polypeptides, and peptides composed of more than 50 amino acid residues are usually called proteins. Insulin contains 51 amino acids and is a protein. Glucagon contains only 29 amino acids, so it can only be called a polypeptide.

Each amino acid that makes up a peptide molecule is not a complete molecule because it participates in the formation of peptide bonds, so it is called an amino acid residue (residue). In a peptide molecule, the N-terminal amino acid is the first amino acid (residue). When naming, just add the word "acyl" after each amino acid name.

Representation and naming of tripeptides

Nonribosomally synthesized peptides and ribosomally synthesized peptides

Natural active peptide----Glutathione

Physicochemical properties of oligopeptides

A biological macromolecular substance with a certain spatial structure composed of different amino acids connected by peptide bonds (the number of amino acids is greater than 50)

"Central Dogma"

The function of DNA lies in its primary structure: the function of protein lies in its three-dimensional structure

diversity of composition

Variety of sizes

structural diversity

Diversity of functions

In the plane of the peptide, the two Cα can be in cis or trans configuration. The trans configuration is more stable than the cis configuration. (Except Pro)

primary structure of protein

protein secondary structure

Tertiary structure of protein

quaternary structure of protein

protein subunits

Definition of protein folding Basic rules of protein folding Chaperone Diseases related to protein misfolding