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Environmental Technologies Part 2

Tham khảo tài liệu 'environmental technologies part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Biosensors for Life Sciences 13 Michaelis-Menten allure can be seen with a linear dependence for concentration of substratum smaller then 4-10-4M characterised by a correlation coefficient close to the unitary value. It was characterized the kinetic of the reaction corresponding to immobilised acetylcholinesterase. For this it was realised the Lineweaver-Burk representation Fig. 5. . Fig. 5. Lineaweaver-Burk representation for immobilised of genetic modified Dm E107Y acetylcholinesterase using M.4.1. sol-gel method working potential 100mV vs Ag AgCl The same steps were followed for mutant of AChE Drosophila melanogaster E107W and AChE from Electric eel. Using the information from calibration curves and from Lineweaver-Burk equations there were determinate biosensors sensitivities and apparent Michaelis-Menten constants Table 5. . Parameter AChE Electric eel Mutant AChE Drosophila melanogaster E107W E107Y Km mM - for free enzyme 0 21 0 55 0 51 Km mM - for immobilised enzyme 0 29 0 66 0 87 Biosensor sensitivity mA L mol 245 75 80 53 315 01 I max nA 144 92 82 64 434 78 Table 5. Michaelis-Menten constants for AChE from Electric eel and mutants Drosophila melanogaster E107W and E107Y and the slopes of the linear dependencies from the calibration curves A lower Michaelis-Menten constant for Electric eel AChE indicates a higher affinity of enzyme for their substrate Coman et al 2003 and the slope indicates a higher transformation rate of the substrate in reaction product comparing with mutant Drosophila melanogaster AChE E107W and E107Y . 14 ENVIRONMENTAL TECHNOLOGIES New Developments The influence of organic solvents over the enzyme biosensors answers was also tested. Depending by the solvent used and their quantity used in the experimental studies it was necessary to study the enzyme behaviour in these organic media . For the inhibition tests in presence of organophosphorus pesticides there were used small volumes of pesticide solutions in acetonitrile 2-20 pL in 5 mL .