", an organic compound derived from dehydration of amino acids, containing carboxyl and amino groups, and being an amphoteric compound." Also known as a peptide.

Ii. One of the amides. It is made up of two or more amino acids by combining the amino group of one amino acid with the carboxyl group of the other amino acid. An amino acid cannot be called a peptide, nor can it be synthesized. It must be a compound of two or more amino acids linked by a peptide bond. A compound where two amino acids are linked by a peptide bond is called a dipeptide; "A compound of three amino acids linked by peptide bonds is called a tripeptide, and by analogy, a compound of thirty-four amino acids linked by peptide bonds is called a thirty-four peptide."

Third, they are bioactive substances involved in a variety of cellular functions in organisms. Hundreds of peptides have been found in organisms, which are essential participants in the body to complete a variety of complex physiological activities. All cells synthesize peptidic substances, and their functional activities are also regulated by peptides. It is involved in hormones, nerves, cell growth and reproduction, and its importance lies in the regulation of various organs and cells in the body. The physiological and pharmacological effects of enzymatic peptides are mainly to activate relevant enzyme systems in the body, promote the permeability of intermediate metabolic membranes, or control DNA transcription or translation to affect specific protein synthesis, and finally produce specific physiological or pharmacological effects. Peptide is better than amino acid, one is faster than amino acid absorption; Second, it is absorbed by the body in its complete form; The third is active absorption (amino acids are passive absorption); The fourth is low consumption. Compared with amino acids, peptide absorption has the characteristics of low consumption or no energy consumption. After peptide is absorbed through the duodenum, it directly enters the blood circulation and transports its energy and nutrition to various parts of the human body. Fifth, the absorption of peptide is more unsaturated than that of amino acids; Sixth, there are only 20 kinds of amino acids with countable functions, while peptides use amino acids as substrates and can be synthesized in hundreds of thousands. Peptides are small molecules of degraded collagen, containing amino acid groups, and belong to raw material products. Peptides are also innate components of the human body, which are chains of amino acids. A protein, as we know it, is a polypeptide chain. "Peptides composed of different amino acids that differ in their composition and order." A compound connected by a peptide bond of two amino acids is called a "dipeptide", and so on, a compound composed of 9 amino acids is called a "nonapeptide", a peptide composed of multiple amino acids (generally 50, also known as 100) is called a polypeptide, and the amino acid unit composed of a polypeptide is called an amino acid residue. Peptide bonds link