Amino acids are amphoteric, both acidic and basic.

Most common amino acids are alpha-amino acids, which contain -COOH and -NH2. -COOH ionizes H+ to be acidic, and -NH2 combines with water to form -NH3 and -OH to be alkaline, which usually ionize to a similar degree, making the amino acid solution neutral. When there is more -COOH than -NH2 in an amino acid molecule, it is acidic; and when there is more -NH2 than -COOH in an amino acid molecule, it is basic.

Extended information:

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1, common acidic amino acids

(1) aspartic acid: also known as aspartic acid, is an alpha-amino acid, the L-isomer of aspartic acid is one of the 20 protein amine acids, the construction unit of proteins, and its codons are GAU and GAC, which are acidic with glutamic acid amino acids.

(2) Glutamate: Glutamate is one of the basic amino acids for nitrogen metabolism in living organisms and is metabolically important. A variety of foods as well as the human body contains glutamate, which is one of the structural amino acids of proteins or peptides, but also free amino acids, L-type amino acids are more concentrated.

2, common alkaline amino acids

(1) lysine: lysine is an essential alkaline amino acid, is one of the essential amino acids, can promote human development, enhance immune function, and has the effect of improving the function of the central nervous system. Because the lysine content in cereal food is very low, and it is easy to be destroyed during processing and lack of, so it is called the first limiting amino acid.

(2) histidine: α-amino β-imidazolylpropionic acid, belonging to the basic amino acids or heterocyclic amino acids, ? Under the action of histidine decarboxylase, histidine decarboxylates to form histamine. Histamine has a strong vasodilatory effect and is associated with a variety of allergic reactions and inflammation. In addition, histamine stimulates pepsin and gastric acid.

Baidu Encyclopedia - Amino Acids

Baidu Encyclopedia - Acidic Amino Acids

Baidu Encyclopedia - Basic Amino Acids