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Investigation of the microenvironments of nonionic Tween 85 reverse micelle systems and mixed Tween 85 reverse micelle systems and their utilization as reaction media for enyzme catalysis

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Investigation of the microenvironments of nonionic Tween 85 reverse micelle systems and mixed Tween 85 reverse micelle systems and their utilization as reaction media for enyzme catalysis
作者:	Mohammed, Rachel Stacey Anastasia.
面頁冊數:	115 p.
附註:	Source: Dissertation Abstracts International, Volume: 65-04, Section: B, page: 1838.
附註:	Supervisor: Linda B. McGown.
Contained By:	Dissertation Abstracts International65-04B.
標題:	Chemistry, Analytical.
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3129070
ISBN:	049676330X

Investigation of the microenvironments of nonionic Tween 85 reverse micelle systems and mixed Tween 85 reverse micelle systems and their utilization as reaction media for enyzme catalysis
Mohammed, Rachel Stacey Anastasia.

Investigation of the microenvironments of nonionic Tween 85 reverse micelle systems and mixed Tween 85 reverse micelle systems and their utilization as reaction media for enyzme catalysis [electronic resource] - 115 p.

Source: Dissertation Abstracts International, Volume: 65-04, Section: B, page: 1838.

Thesis (Ph.D.)--Duke University, 2003.

The first part of this dissertation focuses on the effects of nonionic surfactants on the catalytic activity of the interfacial enzyme, Chromobacterium Viscosum lipase, in reverse micelle systems. The reverse micelle system formed by the nonionic surfactant poly(oxyethylene) sorbitan trioleate (Tween 85) was used in these studies. The catalytic efficiency, kcat/KM, of lipase is shown to be an order of magnitude lower in the Tween 85 reverse micelle system compared to the previously studied anionic sodium bis(2-ethylhexyl) sulfosuccinate (AOT) system, indicating that the nonionic environment affects the interfacial activation of the enzyme. The buffer system used in the nonionic Tween 85 system was also shown to affect lipase activity. On the other hand, lipase activity in AOT reverse micelles was not affected by the nature of the buffer used as the aqueous phase. The anionic bile salt, sodium taurocholate (NaTC), had a similar influence on lipase activity in the Tween 85 revere micelle as in the anionic AOT system, namely, that the incorporation of the bile salt in the interfacial region of the reverse micelles increases lipase activity. Studies of the nonionic bile salt, N,N,bis(3-D-gluconamidopropyl)cholamide (BigCHAP), on lipase activity in AOT reverse micelles proved to be inconclusive due to the low solubility of BigCHAP in this system compared to previously studied, ionic bile salts.

ISBN: 049676330XSubjects--Topical Terms:

224793
Chemistry, Analytical.

Investigation of the microenvironments of nonionic Tween 85 reverse micelle systems and mixed Tween 85 reverse micelle systems and their utilization as reaction media for enyzme catalysis
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520 # $a The first part of this dissertation focuses on the effects of nonionic surfactants on the catalytic activity of the interfacial enzyme, Chromobacterium Viscosum lipase, in reverse micelle systems. The reverse micelle system formed by the nonionic surfactant poly(oxyethylene) sorbitan trioleate (Tween 85) was used in these studies. The catalytic efficiency, kcat/KM, of lipase is shown to be an order of magnitude lower in the Tween 85 reverse micelle system compared to the previously studied anionic sodium bis(2-ethylhexyl) sulfosuccinate (AOT) system, indicating that the nonionic environment affects the interfacial activation of the enzyme. The buffer system used in the nonionic Tween 85 system was also shown to affect lipase activity. On the other hand, lipase activity in AOT reverse micelles was not affected by the nature of the buffer used as the aqueous phase. The anionic bile salt, sodium taurocholate (NaTC), had a similar influence on lipase activity in the Tween 85 revere micelle as in the anionic AOT system, namely, that the incorporation of the bile salt in the interfacial region of the reverse micelles increases lipase activity. Studies of the nonionic bile salt, N,N,bis(3-D-gluconamidopropyl)cholamide (BigCHAP), on lipase activity in AOT reverse micelles proved to be inconclusive due to the low solubility of BigCHAP in this system compared to previously studied, ionic bile salts.
520 # $a The second part of this dissertation describes the investigation of the microenvironments of Tween 85 reverse micelles using the absorption probes methyl orange (MO) and methylene blue (MB). The water contained in the polar inner core of the nonionic reverse micelles has a much lower polarity than that of bulk water, and the presence of the water soluble cosurfactant, 2-propanol, further decreases the polarity of the aqueous pool. The 2-propanol cosurfactant is also shown to increase the fluidity of the Tween 85 reverse micelle interfacial region allowing the incorporation of bile salt into the reverse micelle. These studies show that, the aqueous pool forms when the water content has a value of 30 or greater, and that there are three states of water in the polar inner core region: primary bound water, secondary bound water, and 'free' water.
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