HELICOBACTER-PYLORI UREASE - PROPERTIES AND ROLE IN PATHOGENESIS
HELICOBACTER-PYLORI UREASE - PROPERTIES AND ROLE IN PATHOGENESIS
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DOI：
10.3109/00365529109098223
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发表时间：
1991-01-01
影响因子：
1.9
通讯作者：
FOXALL, PA
中科院分区：
文献类型：
--
作者：
MOBLEY, HLT;HU, LT;FOXALL, PA
尿素酶（尿素酰胺水解酶，EC 3.5.1.5）催化尿素水解产生氨和二氧化碳。 自从发现幽门螺杆菌是人类胃炎的病原体以来，对这种酶的研究已经获得了动力。 每种微生物的显著高的脲酶活性已经作为在脲酶活组织检查试验和尿素呼气试验中微生物存在的诊断试验的基础。 尿素酶在H. pylori发病机制 尿素水解生成氨可能使这种酸敏感生物体能够在胃粘膜中存活。 尿素水解产生的氨也可能在胃上皮内产生严重的细胞毒性作用。 这种酶还在急性感染期间激发强烈的免疫应答，表明这种丰富的抗原容易被免疫系统利用。 血清IgG滴度的增加预示着正在进行的感染。 关于脲酶的分子生物学研究已经取得了很大进展。 高分子量蛋白质（几个研究人员估计为300-520 kDa）已被纯化，揭示了29.5 kDa和66 kDa的两个不同的亚基，与其他微生物尿素酶相比，独特的亚基结构。 然而，氨基酸序列仍然很保守，与其他细菌尿素酶和杰克豆，刀豆。 此外，还对H. pylori的基因已经被克隆、测序并通过聚合酶链反应扩增。
Urease (urea amidohydrolase, EC 3.5.1.5) catalyzes the hydrolysis of urea to yield ammonia and carbon dioxide. Research on this enzyme has gained momentum since the discovery of Helicobacter pylori as a causative agent of human gastritis. The remarkably high urease activity of each organism has served as the basis of diagnostic tests for the presence of the organism in the urease biopsy test and urea breath test. Urease undoubtedly plays a central role in H. pylori pathogenesis. Hydrolysis of urea with generation of ammonia may enable survival of this acid-sensitive organism in the gastric mucosa. Ammonia generated by urea hydrolysis may also produce severe cytotoxic effects within gastric epithelium. The enzyme also elicits a strong immune response during acute infection, suggesting that this abundant antigen is readily available to the immune system. An increase in serum IgG titer is predictive of ongoing infection. Much progress has been made with regard to the molecular biology of urease. The high molecular weight protein (estimated by several investigators to be 300-520 kDa) has been purified, revealing two distinct subunits of 29.5 kDa and 66 kDa, a unique subunit structure as compared with other microbial ureases. However, amino acid sequences are nevertheless well conserved when compared with other bacterial ureases and that of the jack bean, Canavalia ensiformis. Furthermore, genes encoding urease of H. pylori have been cloned, sequenced, and amplified by the polymerase chain reaction.