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Why is GABA also called 4-aminobutanoic acid?

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oxidation of alcohols — carboxylic acid Alcohols may be oxidized to give aldehydes, ketones, and carboxylic acids. The oxidation of organic compounds generally increases the number of bonds from carbon to oxygen, and it may decrease the number of bonds to hydrogen.

GABA is called 4-aminobutanoic acid because of the rules governing the nomenclature of carboxylic acids.

Under the IUPAC system, the name of a carboxylic acid is based on the longest carbon chain containing the carboxyl group. The chain is numbered starting with the carboxyl carbon as carbon 1. Because the molecule has a four-carbon chain with an amino group attached to the fourth carbon, it is systematically named 4-aminobutanoic acid.1

In contrast, the name "gamma-aminobutyric acid" (GABA) is a common name. In common nomenclature, substituents are designated by Greek letters, with the counting beginning at the carbon atom adjacent to the carboxyl group rather than the carboxyl carbon itself. Therefore, the carbon at the 4-position in the IUPAC system corresponds to the gamma ( $γ$ ) position in the common naming system.1