Determination of total cholesterol in serum by cholesterol oxidase and cholesterol esterase co-immobilized on to cellulose acetate membrane
2003
Hamid, S.B.S. (Universiti Sains Malaysia, Kelantan (Malaysia). School of Medical Sciences) | Omar, I.C.
Optimization of the co-immobilized cholesterol esterase and cholesterol oxidase preparations on to cellulose acetate membrane by absorption was performed. A maximum absorption of 75% for cholesterol oxidase and 63% for cholesterol esterase was obtained under the conditions consisting of agitation rate of 70 oscillations per min for 18 h using 0.06 U cm-2 of cholesterol esterase and 0.08 U cm-2 of cholesterol oxidase at 37 degree centigrade and pH 7.4. The enzyme activities and stabilities were improved when treated with 1.5% of glutaraldehyde. A significant and satisfactory stability of 8 repeated uses of the co-immobilized preparations was obtained with a t 1/2 of 15 consecutive uses. When compared to the commercially available Sera-Pak(R) (Bayer corporation) and CHOD- PAP (Chema diagnostica), the co-immobilized enzymes preparation showed a significant correlation with an r value of 0.95 and 0.99, respectively.
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