. Biophysical science. Biophysics. 18 : 1/ Enzymes: Kinetics of Oxidations 339 The technical difficulties of measuring tlj2^ and pm are less than those of measuring tpj2. Accordingly, Equations 11 and 12 are convenient for precise measurement of k1 and k3. These values agree with those found by using Equations 5 and 7 and those found by using Equations 9 and 10. Computed for "1 *2 I06M" = 0 sec k3a = sec"1 e = I0"6M i0 = 4x|6"6M *. Figure 5. The intermediate complex for the peroxidatic reaction of catalase. The quantities shown above are used to compute k1 and k3.
. Biophysical science. Biophysics. 18 : 1/ Enzymes: Kinetics of Oxidations 339 The technical difficulties of measuring tlj2^ and pm are less than those of measuring tpj2. Accordingly, Equations 11 and 12 are convenient for precise measurement of k1 and k3. These values agree with those found by using Equations 5 and 7 and those found by using Equations 9 and 10. Computed for "1 *2 I06M" = 0 sec k3a = sec"1 e = I0"6M i0 = 4x|6"6M *. Figure 5. The intermediate complex for the peroxidatic reaction of catalase. The quantities shown above are used to compute k1 and k3. The curve illustrated is based on an analog-computer study. Similar curves can be found experi- mentally both for the enzyme-substrate complex of catalase and for complex II of peroxidase. After B. Chance, "Velocity Constants in Enzyme Reactions," Arch. Biochem. Biophys. 71 : 130 (1957). The rate constant k2 is more difficult to determine precisely. An upper limit for k2 can be found by making suitable approximations from the data at the end of the reaction. Also, as noted previously, knowing kx and k3 independently, one can obtain an estimate of k2 from the apparent Michaelis constant. Some typical values for the different constants for bacterial catalase are X = H202 k1 = 2 x 10' CH3OOH x 106 C2H5OOH x 104 M sec S =HCOONa £3 = 175 CH3OH 91 C2H5OH 13 M -1 sec -1 An upper limit on the constant k2 can be estimated as k2 ^ sec' The other type of reaction discussed for catalase is the destruction of hydrogen peroxide. This reaction is similar to the peroxidatic reactions,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ackerman, Eugene, 1920-. Englewood Cliffs, N. J. , Prentice-Hall
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