The mixed function oxidase system of the house fly, Musca domestica, L.
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| Other Authors: | , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1983.
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| Subjects: | |
| Online Access: | Link to OAKTrust Copy Link to ProQuest Copy |
| Abstract: | The microsomal mixed function oxidase system of the house fly (Musca domestica (L.)) Rutgers diazinon resistant strain was characterized by steady state kinetics with respect to N-demethylation of p-chloro-methylaniline, O-demethylation of methoxyresorufin, epoxidation of aldrin and formation of a metabolite cytochrome P-450 complex during oxidation of piperonyl butoxide. The inhibition of these reactions by juvenile hormone I was competitive for the N-demethylase, epoxidase and the formation of the piperonyl butoxide metabolite complex. Non-competitive inhibition of the O-demethylase reaction was observed. The competitive inhibition of these reactions by juvenile hormone-I in vitro is consistent with the hypothesis that the mixed function oxidase system could participate in the degradation of juvenile hormone in vivo. The reduced piperonyl butoxide metabolite complex and ethyl isocyanide type III spectra exhibited pH dependence which was examined by determining the pH at which the two peak heights were equal (the equilibrium point). This was 8.3 for the reduced piperonyl butoxide metabolite complex, and 9.5 for ethyl isocyanide. These equilibrium points are higher than that of hepatic cytochrome P-450 and indicate that the insect cytochrome P-450 is different from the mammalian enzyme. The piperonyl butoxide metabolite complex was generated in vivo an observation that has never been reported for insects. House fly microsomal cytochrome P-450 was solubilized with less than 50% recovery using cholate. The optimum phosphate concentration (100mM) and cholate concentration (0.4%(w/v)) for minimizing cytochrome P-420 formation and maximizing cytochrome P-450 recovery were determined. Cytochrome P-450 was partially purified from microsomes using cholate solubilization, polyethylene glycol 6000 precipitation and chromatography on DEAE-cellulose, hydroxylapatite and CM-Sephadex. The partially purified preparation had a specific content of 10.1 nmol/mg protein based upon an extinction coefficient of 91 mM('-1) cm('-1) for the reduced CO difference spectra and had an apparent molecular weight of 60,000 when examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. A second cytochrome P-450 containing fraction eluted from DEAE-cellulose with a 0-0.25 M salt gradient. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Biochemistry." |
| Physical Description: | x, 92 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 81-91). |