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151.
Carbon monoxide dehydrogenase (CODH) is the key enzyme of autotrophic growth with CO or CO2 and H2 by the acetyl-CoA pathway. The enzyme from Clostridium thermoaceticum catalyzes the formation of acetyl-CoA from the methyl, carbonyl, and CoA groups and has separate binding sites for these moieties. In this study, we have determined the role of arginine residues in binding of CoA by CODH. Phenylglyoxal, an arginine-specific reagent, inactivated CODH, and CoA afforded about 80-85% protection against this inactivation. The other ligands, such as the carbonyl and the methyl groups, gave no protection. By circular dichroism, it was shown that the loss of activity is not due to extensive structural changes in CODH. Earlier, we showed that tryptophan residues are located at the CoA binding site of CODH [Shanmugasundaram, T., Kumar, G. K., & Wood, H. G. (1988) Biochemistry 27, 6499-6503]. A comparison of the fluorescence spectra of the native and phenylglyoxal-modified enzymes indicates that the reactive arginine residues appear to be located close to fluorescing tryptophans. Fluorescence spectral studies with CoA analogues or its components showed that CoA interacts with the tryptophan(s) of CODH through its adenine moiety. In addition, evidence is presented that the arginines interact with the pyrophosphate moiety of CoA. 相似文献
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The oriVRK2 does not need the function of either trfA+ ortrfA Operon for replication and maintenance of an oriVRK2-containing plasmid inAzotobacter vinelandii. 相似文献
155.
S. Easwaramoorthy H. David G. Santhalakshmi M. Shanmugasundaram V. Nandagopal N. K. Kurup 《BioControl》1990,35(3):385-391
Susceptibility of adults and puparia ofSturmiopsis inferens Tns. [Tachinidae, Diptera] to 9 commonly recommended insecticide sprays against sugarcane pests was determined. The chemicals tested as emulsifiable
concentrates include lindane 0.1%, endosulfan 0.1%, monocrotophos 0.05%, quinalphos 0.05%, malathion 0.1%, dimethoate 0.1%,
cypermethrin 0.01%, fenvalerate 0.01% and decamethrin 0.0014%. Lindane, malathion, dimethoate monocrotophos and quinalphos
were highly toxic, while decamethrin had little harmful effect to the adults when exposed for 6 h to filter paper impregnated
or sugarcane shoot bits sprayed with the chemicals. However, the insecticides had no harmful effect on the puparia and adult
emergence was normal from the puparia sprayed with insecticides.
In another study, susceptibility of adults to soil application of lindane EC, carbofuran G, chlorpyriphos G, Sevidol G and
whorl application of lindane G, chlorpyriphos G and Sevidol G was tested in pot culture. Except for soil application of lindane
EC, all other chemicals had no harmful effect to the adults in pot culture experiment. In a field trial, commonly recommended
insecticides against shoot borer,Chilo infuscatellus Snell.viz., soil application of granules of lindane, carbofuran, chlorpyriphos and Sevidol and folia spray of endosulfan did not affect
the parasite activity.
Institute Publication No 1030. 相似文献
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Natarajan Aravindan Karthigayan Shanmugasundaram Mohan Natarajan 《Molecular and cellular biochemistry》2009,327(1-2):29-37
Conceptual approaches of heat-induced cytotoxic effects against tumor cells must address factors affecting therapeutic index, i.e., the relative toxicity for neoplastic versus normal tissues. Accordingly, we investigated the effect of hyperthermia treatment (HT) on the induction of DNA fragmentation, apoptosis, cell-cycle distribution, NFκB mRNA expression, DNA-binding activity, and phosphorylation of IκBα in the normal human Mono Mac 6 (MM6) cells. For HT, cells were exposed to 43°C. FACS analysis showed a 48.5% increase in apoptosis, increased S-phase fraction, and reduced G2 phase fraction after 43°C treatments. EMSA analysis showed a dose-dependent inhibition of NFκB DNA-binding activity after HT. This HT-mediated inhibition of NFκB was persistent even after 48 h. Immunoblotting analysis revealed dose-dependent inhibition of IκBα phosphorylation. Similarly, RPA analysis showed that HT persistently inhibits NFκB mRNA. These results demonstrate that apoptosis upon HT exposure of MM6 cells is regulated by IκBα phosphorylation mediated suppression of NFκB. 相似文献
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Abstract Certain strains of the nitrogen-fixing cyanobacterium Anabaena were found to release varying quantities of ammonia without any induction, both in the presence and absence of combined nitrogen (nitrate) in the medium, during the different phases of their growth. In general, growth and ammonia release were comparable in both media, although there were strain differences. 3 patterns of ammonia release were observed in different strains during the growth period. They were: (1) release pattern parallel to the growth curve; (2) a continuous increase in release; and (3) release showing a bimodal curve. 相似文献