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91.
Ray SS Tejero J Wang ZQ Dutta T Bhattacharjee A Regulski M Tully T Ghosh S Stuehr DJ 《Biochemistry》2007,46(42):11857-11864
Although nitric oxide (NO) is important for cell signaling and nonspecific immunity in the fruit fly Drosophila melanogaster, little is known about its single NO synthase (dNOS). We expressed the oxygenase domain of dNOS (dNOSoxy), characterized its spectroscopic, kinetic, and catalytic properties, and interpreted them in light of a global kinetic model for NO synthesis. Single turnover reactions with ferrous dNOSoxy showed it could convert Arg to N'omega-hydroxy-l-arginine (NOHA), or NOHA to citrulline and NO, when it was given 6R-tetrahydrobiopterin and O2. The dNOSoxy catalyzed Arg hydroxylation and NOHA oxidation at rates that matched or exceeded the rates catalyzed by the three mammalian NOSoxy enzymes. Consecutive heme-dioxy, ferric heme-NO, and ferric heme species were observed in the NOHA reaction of dNOSoxy, indicating that its catalytic mechanism is the same as in the mammalian NOS. However, NO dissociation from dNOSoxy was 4 to 9 times faster than that from the mammalian NOS enzymes. In contrast, the dNOSoxy ferrous heme-NO complex was relatively unreactive toward O2 and in this way was equivalent to the mammalian neuronal NOS. Our data show that dNOSoxy has unique settings for the kinetic parameters that determine its NO synthesis. Computer simulations reveal that these unique settings should enable dNOS to be a more efficient and active NO synthase than the mammalian NOS enzymes, which may allow it to function more broadly in cell signaling and immune functions in the fruit fly. 相似文献
92.
Srabani De A. K. Dasmahapatra A. K. Ray A. K. Medda 《Neurochemistry international》1989,14(4):461-465
For elucidation of thyroid hormone-induced responsiveness of fish brain, various doses (0.012, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2 and 4 μg/g) of triiodothyronine (T3) were injected in Singi fish, Heteropneustes fossilis (Bloch), for 3 consecutive days and the changes in cytosolic NADP-dependent malic enzyme (ME, EC 1.1.1.40) activity in whole brain tissue were determined. Compared to the control, the ME activity increased with lower doses (0.012, 0.025 and 0.05 μg/g) and decreased with higher doses (1, 2 and 4 μg/g) of T3, showing a biphasic nature of thyroid hormone action. The enzyme activity remained unaltered with 0.1, 0.25 and 0.5 μg of T3/g in comparison to the control. Immersion of the fishes in cycloheximide-containing medium (0.5 mg/l) inhibited the T3 (0.025 μg/g)-induced rise in ME activity. On the other hand, the NAD-dependent cytosolic malate dehydrogenase (EC 1.1.1.37) activity and the total protein content of brain cytosol remained unaltered with all doses of T3 used. The thyroid hormone specificity of cytosolic NADP-dependent malic enzyme in fish brain is thus documented. 相似文献
93.
94.
Archisman Ray Subodha Kumar Karna Trupti Rani Mohanty Himanshu Sekhar Swain Basanta Kumar Das 《Zeitschrift fur angewandte Ichthyologie》2019,35(4):1050-1052
Length–weight relationships (LWRs) were determined for seven riverine fish species from the river Ganga, India. Specimens were collected on a bi‐monthly basis from April 2017 to December 2018 using gill nets (mesh size 22–34 mm), cast nets (mesh size 16 mm) and bag nets (mesh size 14–22 mm). Total length was measured to the nearest 0.1 cm using a digital caliper and weight was recorded to the nearest 0.01 g on an electronic balance. From estimated length–weight relationships, the values for parameter “a” ranged from 0.004 (Bregmaceros mcclellandi and Setipinna tenuifilis) to 0.014 (Brachirus pan). Likewise, the values for the parameter “b” of the equation ranged from 2.958 (Bagarius bagarius) to 3.124 (Bregmaceros mcclellandi) and r2 from 0.978 (Gonialosa manmina) to 0.996 (Brachirus pan). 相似文献
95.
The psychrotrophic, dimorphic yeast Candida humicola, isolated from Antarctic soil, secretes an acidic protease into the medium. The secretion of this protease by C. humicola was found to be dependent on the composition of the medium. In YPD or yeast nitrogen base medium containing either amino acids or ammonium sulfate as the nitrogen source, the activity of the protease in the medium was low (basal level). However, when yeast nitrogen base medium was depleted of amino acids or ammonium sulfate and supplemented with proteins, the activity of the enzyme increased. The secretion of the enzyme was greater during exponential growth at low temperatures than during growth at higher temperatures. The purified protease had a molecular mass of 36,000 Da and was inhibited by pepstatin, iodoacetamide, and sodium dodecyl sulfate. Despite the prevalent cold temperatures in Antarctica, this extracellular protease of the psychrotrophic yeast C. humicola was active at temperatures ranging from 0 to 45 degrees C, with an optimum activity at 37 degrees C. 相似文献
96.
R-banding and nonisotopic in situ hybridization: precise localization of the human type II collagen gene (COL2A1) 总被引:13,自引:4,他引:13
Ei-ichi Takahashi Tada-aki Hori Peter O'Connell Mark Leppert Ray White 《Human genetics》1990,86(1):14-16
Summary A new mapping system, based on nonisotopic in situ hybridization combined with fluorescent staining of replicated prometaphase R-bands, is described. Replication of the bands is achieved by treatment of thymidinesynchronized cells with bromodeoxyuridine. The human COL2A1 gene was mapped to band 12q13.11–q13.12 in this manner, to illustrate the potential of the technique for improving the precision of chromosomal mapping and physical ordering of genes. 相似文献
97.
Otto D. Hensens Ray S. Dewey Jerrold M. Liesch Mary A. Napier Robert A. Reamer Jack L. Smith Georg Albers-Schönberg Irving H. Goldberg 《Biochemical and biophysical research communications》1983,113(2):538-547
Spectroscopic evidence suggests the presence of a highly strained ether ring (Fig. 1) (possibly an epoxide) in the C12-subunit of the previously determined partial structure (Fig. 2) of the major neocarzinostatin chromophore (NCS-Chrom ) which completes assignment of all the oxygens in the molecule. The main product from mercaptan treatment suggests opening of the ether ring involving the addition of one molecule of mercaptan as well as reduction of the C12-substructure, whereas a parallel two-step reduction occurs on NaBH4 treatment. Both reactions occur with rearrangement of the C12-substructure and the implication for the mechanism of action of NCS-Chrom in DNA strand scission activity is discussed. The evidence suggests a downward revision of the molecular formula for NCS-Chrom as well as minor components and by two protons. 相似文献
98.
C. Marjorie Aelion J. N. Shaw R. P. Ray M. A. Widdowson H. W. Reeves 《Soil & Sediment Contamination》1996,5(3):225-241
Portable meters and simplified gas Chromatographic (GC) techniques were investigated for monitoring volatile hydrocarbon (HC), CO2, and O2, concentrations in groundwater, exhaust gases, and soil vapor during in situ remediation using soil vapor extraction (SVE) and air sparging (AS). Results of groundwater samples analyzed in‐house using a headspace technique compared well to split samples analyzed by a certified analytical laboratory (r2 = 0.94). SVE exhaust gas HC and CO2 concentrations measured using a GT201 portable HC/O2 meter and a RA‐411A meter (GasTech), respectively, were highly correlated with in‐house laboratory GC analyses (r2 = 0.91). O2 concentrations fell in a small range and meter analyses were not well correlated with laboratory analyses. Results of soil gas monitoring were not as well correlated as those for exhaust gases for HC, CO2, or O2, perhaps due to environmental conditions such as changes in relative humidity or the wider range of soil gas values. Overall, the meters were good indicators of vapor contamination, they greatly simplified estimates of total HC mass removal, and they allowed estimates of the biological contribution to contaminant removal during the remediation process. 相似文献
99.
Mycobacillin non-producers, whether sporogenous or asporogenous, possess less exoprotease, but effective exoprotease producers are not always good mycobacillin yielders. There might exist a minimum level of exoprotease formation for elaboration of mycobacillin. 相似文献