What is a "peptide"? What are there?

Peptide (English: peptide, from Greek, meaning "digestion"), formerly known as peptide, is a naturally occurring biological small molecule, between amino acid and protein.

Because the amino acid molecule is the smallest and the protein is the largest, it is a short chain composed of amino acid monomers and connected by peptide (amide) bonds. This valence bond is formed when the carboxyl group of one amino acid reacts with the amino group of another amino acid.

There are dipeptides, tripeptides and even polypeptides, 2-20 peptides belong to oligopeptides, and 20-50 peptides belong to polypeptides. Generally, peptides with less than 10 peptides are more practical in medicine and commerce.

Extended data:

Peptides can be hydrolyzed from dietary protein by chemical methods or obtained artificially. It is composed of two or more amino acids, which is very important in the regulation of cell physiology and metabolic function. Most peptides are unstable in nature, so long-term storage should be moisture-proof and placed below 4℃.

Peptides are chain molecules formed by dehydration and condensation of amino (-NH2) and carboxyl (-COOH) of amino acids to form peptide bonds.

Peptide bond is a -CO-NH- bond formed by dehydration and condensation reaction between one amino acid and the amino group of the next amino acid. It has the property of double bond and is on the same plane as the six adjacent atoms, so C-N can't rotate freely. Peptide bond is the bond that constitutes the structure of protein.

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