STRUCTURE AND FUNCTION OF ENZYMES INVOLVED IN THE METABO

聚唾液酸是几种致病细菌的致病因子。 脑膜炎。它也存在于发育中的人脑中。这 随之而来的是常见的免疫原性差 多糖阻碍了其作为疫苗的使用。几种酶所需的 聚唾液酸的生物合成也是唾液酸化所必需的。 脊椎动物糖蛋白。这个项目的目标是 描述这些酶的结构和功能，以及它们的用途 它们是理解细菌和人类唾液酸化的工具。 与E.ColicMP-唾液酸氨基酸序列的比较 合成酶是唾液酸化反应中的一种关键酶，其序列为 其他病原细菌中存在的酶表明氨基酸是保守的。 在氨基末端序列中已鉴定出几个碱性残基 定点突变为活性残基的E.ColicMP-sialic 酸性合成酶。这些残基在所有已知的细菌中都是保守的 CMP-neuAc合成酶。大肠杆菌突变株的动力学分析 这些酶表明这些残留物可能在 产物的形成和核苷酸底物的相互作用。这个 从牛脑下垂体中提纯同源酶至均一 腺体。

Polysialic acid is a virulence factor for several bacteria causing meningitis. It is alos present in the developing human brain. This common occurrence along with the poor immunogenicity of this polysaccharide hampers its use as a vaccine. Several enzymes required for the biosynthesis of polysialic acid are also required for sialylation of vertebrate glycoproteins. The objective of this project is to characterize the structure and function of these enzymes and the use of them as tools for understanding sialylation in bacteria and humans. Comparison of the amino acid sequence with of the E. coli CMP-sialic acid synthetase, an essential enzyme in sialylation, with sequences of the enzyme present in other pathogenic bacteria suggest conserved amino acids. Several basic residues have been identified in the amino terminal sequence by site directed mutagenesis as active residue in the E. coli CMP-sialic acid synthetase. These residues have are conserved in all known bacterial CMP-neuAc synthetase enzymes. Kinetic analysis of the E. coli mutant enzymes suggests these residues may play an essential role in the formation of product and the interaction of nucleotide substrate. The homologous enzyme has been purified to homogeniety from bovine pituitary glands.