Please cite this article as: D. Oancea, Alexandrina Stuparu, Madalina Nita, Mihaela Puiu, Adina Raducan, Estimation of the overall kinetic parameters of enzyme inactivation using an isoconversional method, Biophysical Chemistry (2008Chemistry ( ), doi: 10.1016Chemistry ( /j.bpc.2008 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT ABSTRACTAn isoconversional method is proposed in order to calculate the kinetic parameters of enzyme inactivation. The method provides an efficient and low-cost procedure to describe both operational and thermal inactivation. Unlike the ordinary kinetic assays performed at constant enzyme concentration and at various substrate concentrations, the isoconversional method requires several extended kinetic curves for constant initial substrate concentration and different enzyme concentrations. The procedure was tested and validated using simulated data obtained for several kinetic models frequently discussed in the literature. After the validation, the isoconversional method was used for the investigation of the thermoinactivation of urease during urea hydrolysis in self buffered medium and the operational inactivation (destructive oxidation by excess peroxide) of catalase at high concentration of hydrogen peroxide. The results showed that the isoconversional method gives good results of global inactivation constant for both simple and more complex models.

We describe a procedure to suspend single walled carbon nanotubes with poly(3-dodecylthiophene-2,5-diyl) and to purify them using density gradient centrifugation with 2,4,6-tribromotoluene or dodecyloxy-2,4,6-triiodobenzene as density gradient medium. In contrast to fluorene-based polymers, (n,m) selective solubilization is not observed.

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