GLYCOCONJUGATES OF LEISHMANIA

利什曼病是人类的主要健康问题，由 利什曼原虫属的原生动物寄生虫。磷脂多糖(LPG)是 前鞭毛体表面的一种重要大分子 这些寄生虫被认为是多功能的。从结构上讲，液化石油气 由四个结构域组成：(I)赖索-L-O-烷基磷脂酰肌醇 锚基，(Ii)磷酸糖核，(Iii)重复的聚合物 通过磷酸二酯桥连接在一起的糖单元，和(Iv)a 末端小而不还原的低聚糖。这个 LPG的脂锚和磷糖核心区在 利什曼原虫种类繁多，而糖类有变异性 重复磷酸化糖单元的组成和序列 和盖子结构。虽然已经在以下方面取得了重大进展 液化石油气的结构-功能关系有待进一步研究 关于种间差异和种内发育 液化石油气结构的改进。确定这些结构性差异 伴随着这种重要糖偶联物的生物合成和周转 也将是我们研究的重点。这样做的具体目的是 适用范围如下： L。液化石油气结构分析续论。具体地说， 杜氏乳杆菌印度分离株和日本血吸虫分离株液化石油气的结构 巴西乳杆菌和亚马孙乳杆菌将被阐明。 2.液化石油气生物合成的生化分析。两种关键酶 (甘露糖磷酸转移酶和阿拉伯糖基转移酶)与液化石油气有关 生物合成将被提纯和鉴定。 3.液化石油气周转率的表征。寄生虫对液化石油气的周转 而液化石油气在巨噬细胞被前鞭毛体感染后的命运将是 调查过了。 通过这些研究，我们希望有助于对角色的理解 LPG在利什曼病的发病机制中发挥作用并提供一种 设计化疗方案的生物化学原理 利用其独特的结构。

Leishmaniasis is a major health problem to humans and is caused by protozoan parasites of the genus Leishmania. Lipophosphoglycan (LPG) is an important macromolecule on the surface of the promastigote form of these parasites and is believed to be multifunctional. Structurally, LPG is composed of four domains: (i) a lyso-l-O-alkylphosphatidylinositol anchor, (ii) a phosphosaccharide core, (iii) a polymer of repeating saccharide units linked together by phosphodiester bridges, and (iv) a small, capping oligosaccharide at the terminal, non-reducing end. The lipid anchor and phosphosaccharide core regions of LPG are conserved among various Leishmania species, whereas there is variability of sugar composition and sequence in the repeating phosphorylated saccharide units and the capping structure. While significant progress has been made on structure-function relationships of LPG, much more remains to be learned concerning interspecies differences, and intraspecies developmental modifications of LPG structure. Determining these structural differences along with the biosynthesis and turnover of this important glycoconjugate will also be a focus of our research. The specific aims of this application are as follows: l. Continuation of structural analysis of LPGs. Specifically, the structure of LPG from Indian isolates of L. donovani and from isolates of L. braziliensis and L. amazonensis will be elucidated. 2. Biochemical analysis of LPG biosynthesis. Two key enzymes (mannosylphosphate transferase and arabinosyltransferase) involved in LPG biosynthesis will be purified and characterized. 3. Characterization of LPG turnover. The turnover of LPG by the parasite and the fate of LPG upon infection of macrophages by promastigotes will be investigated. From these studies, we hope to contribute to the understanding of the role LPG plays in the pathogenesis of leishmaniasis and to provide a biochemical rationale for the design of chemotherapeutic regimens that exploit its unique structure.