Silipo Alba, Molinaro Antonio
Dipartimento di Chimica Organica e Biochimica, Università di Napoli Federico II, Complesso Universitario Monte Santangelo, Via Cintia 4, Napoli, I-80126, Italy.
Subcell Biochem. 2010;53:69-99. doi: 10.1007/978-90-481-9078-2_4.
Bacterial lipopolysaccharides (LPSs) are the major component of the outer membrane of Gram-negative bacteria. They have a structural role since they contribute to the cellular rigidity by increasing the strength of cell wall and mediating contacts with the external environment that can induce structural changes to allow life in different conditions. Furthermore, the low permeability of the outer membrane acts as a barrier to protect bacteria from host-derived antimicrobial compounds. Lipopolysaccharides are amphiphilic macromolecules generally comprising three defined regions distinguished by their genetics, structures and function: the lipid A, the core oligosaccharide and a polysaccharide portion, the O-chain. In some Gram-negative bacteria LPS can terminate with the core portion to form rough type LPS (R-LPS, LOS). The core oligosaccharide is an often branched and phosphorylated heterooligosaccharide with less than fifteen sugars, more conserved in the inner region, proximal to the lipid A, and often carrying non-stoichiometric substitutions leading to variation and micro-heterogeneity. The core oligosaccharide contributes to the bacterial viability and stability of the outer membrane, can assure the serological specificity and possesses antigenic properties.
细菌脂多糖（LPSs）是革兰氏阴性菌外膜的主要成分。它们具有结构作用，因为它们通过增强细胞壁强度和介导与外部环境的接触来促进细胞刚性，这种接触可诱导结构变化以适应不同条件下的生存。此外，外膜的低渗透性起到屏障作用，保护细菌免受宿主来源的抗菌化合物的侵害。脂多糖是两亲性大分子，通常由三个通过其遗传学、结构和功能区分的特定区域组成：脂质A、核心寡糖和多糖部分O链。在一些革兰氏阴性菌中，LPS可以以核心部分结尾，形成粗糙型LPS（R-LPS，LOS）。核心寡糖是一种通常带有分支且磷酸化的杂寡糖，糖数少于15个，在靠近脂质A的内部区域更保守，并且常常带有非化学计量的取代基，导致变异和微观异质性。核心寡糖有助于细菌的生存能力和外膜的稳定性，可确保血清学特异性并具有抗原特性。
