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Tuyển tập các báo cáo nghiên cứu khoa học quốc tế về bệnh thú y đề tài: Activation domain in P67phox regulates the steady state reduction of FAD in gp91phox | J. Vet. Sci. 2000 1 1 27-31 JOURNAL OF Veterinary Science Activation domain in P67p x gp91p x regulates the steady state reduction of FAD in Chang-Hoon Han and Mun-Han Lee1 Department of Biochemistry Swiss Federal Institute of Technology in Zurich Universitatstrasse 16 8092 Zurich Switzerland Department of Biochemistry College of Veterinary Medicine Seoul National University Suwon 441-744 Korea An activation domain in p67 x residues 199-210 is critical for regulating NADPH oxidase activity in cell-free system 10 To determine the steady state reduction of FAD thioacetamide-FAD was reconstituted in gp9 r x and the fluorescence of its oxidised form was monitored. Omission of p67 x decreased the steady state reduction of the FAD from 28 to 4 but omission of p47 x had little effect. A series of the truncated forms of p67 x were expressed in E.coli to determine the domain in p67 x which is essential for regulating the steady state of FAD reduction. The minimal length of p67p x for for regulating the steady state of FAD reduction is shown to be 1-210 using a series of truncation mutants which indicates that the region 199-210 is also important for regulating electron flow within flavocytochrome b558. The deletion of this domain not only decreased the superoxide generation but also decreased the steady state of FAD reduction. Therefore the activation domain on p67p x regulates the reductive half-reaction for FAD consistent with a dominant effect on hydride electron transfer from NADPH to FAD. Key words the activation domain on p67 x the steady state of FAD reduction. Introduction Neutrophiles and macrophages produce superoxide and other reactive oxygen species that participate in intracellular killing of phagocytized microorganisms 2 5 . Superoxide generation is catalyzed by NADPH oxidase which consists of both cytosolic factors p47phox and p67phox and plasma membrane associated flavocytochrome b558. In cell resting state cytosolic factors p47phox p67phox exist in the .
