الفهرس 
Introduction and reviewOnly 14 pages are availabe for public view
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Abstract
In this study three types of urease enzyme were isolated from three different species of bacterium; Proteus mirabillis, Helicobacter pylori and Klebsiella pneumonia. The isolated enzymes were purified and characterized using chromatography and FPLC. The three bacterial isolates showed urease production were identified biologically and on molecular biology levels.: 1.Samples were collected from different places, microbiology department, College of Science, Omdurman Islamic University, Cairo internal medicine department of gastrointestinal endoscopy and different medical laboratory from Alexandria. 2.The bacterial isolates obtained from the collected samples were completely purified on specific media and completely identified using different methods Including; culture characteristic, microscopically examination, biochemical reaction and molecular identification using 16S rRNA gene. 3. Urease genes were isolated from the well characterized bacteria and subjected to cloning followed by in vitro transcription in E.coli DH5-α strain. 4.The wild enzyme was purified from Proteus mirabillis using water extract, whenever, the other two recombinant ureases were purified using the His Tag method. 5.All the three enzymes were separated on SDS gel (12%) and it was observed that the molecular weights of the three purified enzymes were (66, 45) ,15 and 45 kDa in Proteus mirabillis, Klebsiella pneumonia and Helicobacter pylori respectively. 6.The maximum activity of the wild urease enzyme was 220 mg/ml and two recombinant ureases (H.pylori and K.peumonia ) were 200, and 190 mg/ml respectively 7.Total of 65 compounds (12 natural, and 53 synthetic) and two crude extracts were screened as urease inhibitors for the three obtained ureases (wild and 2 recombinant) in comparing with the commercial urease (jack bean). 8.For more precaution the 12 selected compounds were exposed to cytotoxicity test and it was found that all are in safe dose.