L-六碳糖形成机制的研究进展

Advances in the formation mechanisms of L-hexoses

摘要:

糖及其衍生物在许多初级或次级代谢过程中发挥着重要作用。糖结构与功能的多样性和糖在疾病诊断与治疗中的重要性推动了糖生物学的快速发展。D型糖，尤其是D-六碳糖在糖中占据着主导地位，L-六碳糖也是许多重要糖蛋白复合物、多糖及抗生素的组成成分。了解L-六碳糖的形成机制有助于理性改造糖的结构并开发其应用价值。L-六碳糖通常由3,5位差向异构酶或5位差向异构酶催化D-六碳糖的C5位异构化形成，这种转变赋予了糖在构型上的多样性，并在许多天然产物中起决定生物活性的作用。对3,5位差向异构酶和5位差向异构酶的功能及晶体结构的研究揭示了L-六碳糖的形成机制。本文综述了L-六碳糖形成过程中不同类型的3,5-位差向异构酶和5-位差向异构酶的催化机制，揭示L-六碳糖在生理和医药领域的重要意义。

Abstract:

Saccharides and their derivatives play prominent roles in many primary and secondary metabolic processes. The diversity of their structures and the significance of sugars in diagnosis and treatment of diseases have promoted the fast development of glycobiology. D-sugars, especially D-hexoses have dominated the carbohydrates region, L-hexoses yet are also frequently observed in some important glycoprotein complexes, polysaccharides and antibiotics. Understanding the formation mechanisms of L-hexoses allow rational manipulation of sugar skeletons and further exploration of their applications. L-hexose is usually generated through epimerization of D-hexose by 3,5-epimerase or 5-epimerase. This transformation expands the diversity of sugar configurations and influences the bioactivities of many natural products. The functional and crystallographic studies of 3,5-epimerases and 5-epimerases have provided profound insights into the formation mechanisms of L-hexoses. In this paper, we summarize the catalytic mechanisms of different 3,5-epimerases and 5-epimerases for L-hexose formation. The physiological importance and biomedical prospects of L-hexoses are also discussed.