Midgut microsomal cytochrome

The microsomal cytochrome P-A50 system In the midguts of southern armyworm larvae oxidises pulegone vitro. The two major products, 9-hydroxypulegone and 10-hydroxypulegone are formed by mlcrosomes from larvae Induced with either pentamethylben-zene or a-plnene. Mlcrosomes from control (un-lnduced) larvae only oxidise trace amounts of the compound. The 9-hydroxypulegone rearranges spontaneously to menthofuran (38). 

Table VII shows the Increase In cytochrome P-450 content In mlcrosomes from southern armyworm larval midguts resulting from dietary exposure to several cyclic monoterpenes ( ). It also shows a closely corresponding Increase In the rate of NADPH oxidation when pyrethrum Is the substrate (R) being oxidised. The microsomal cytochrome P-450 system Is arranged as outlined In Figure 6, consisting of a terminal heme-lron protein that In the oxidised (Fe3+) state binds the substrate (R). The complex undergoes two reductions during which bound molecular oxygen Is converted to free radical species, one of which Is Inserted In the substrate molecule, and the other one forms water. The reductions...

Three acetylenic compounds (Figure 3) were compared to precocene II (1) for their ability to Inhibit JH biosynthesis in vitro, to inhibit oocyte growth in vivo, and to inhibit midgut microsomal (I.e. extra-allatal) cytochrome P-450 monooxygenases. The compounds were chosen to represent an analog of the substrate of the allatal monooxygenase, methyl farnesoate, with the... 

The a-absorption band near 560 nm observed in liver tissue was first referred to as cytochrome hx (see Section IV,B) by Keilin and Hartree (95). The pigment observed in the microsomal fraction of liver was termed cytochrome b by Yoshikawa (96) and m by Strittmatter and Ball (97,98). The name cytochrome bs was given by Pappenheimer and Williams to the pigment found in the midgut of larvae of the Cecropia... 

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