09840 IUPAC Gold Book - lipid A 10.1351/goldbook.09840 09840 current 1 Glycolipid component of lipopolysaccharides (LPSs) that is integrated into the bacterial cell wall and is responsible for the beneficial (immunostimulatory) or toxic (immunopathological) effects of the molecule. The archetypical (Enterobacteriaceae) structure of lipid A consists of a \(\beta\)-1,6-linked d-glucosamine (GlcN) or 2,3-diamino-2,3-dideoxy-d-glucose (GlcN3N) disaccharide (or a mixture of them), which is acylated by varying numbers (usually four to seven) of ester- and amide-linked acyl groups (often termed primary and secondary fatty acids). Phosphate groups and other glycosyl substituents may be linked at the \(\ce{C-1}\) and \(\ce{C-4^{\prime}}\) positions. Lipid A is linked to the core oligosaccharide at the \(\ce{C-6^{\prime}}\) position of the distal sugar unit of lipid A. PAC, 2018, 90, 1121. 'Terminology of bioanalytical methods (IUPAC Recommendations 2018)' on page 1177 (https://doi.org/10.1515/pac-2016-1120) https://goldbook.iupac.org/terms/view/09840/html https://goldbook.iupac.org/terms/view/09840/json https://goldbook.iupac.org/terms/view/09840/plain Citation: 'lipid A' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.09840 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-05-09T21:45:27+00:00