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901.
Immoos CE Bhaskar B Cohen MS Barrows TP Farmer PJ Poulos TL 《Journal of inorganic biochemistry》2002,91(4):635-643
The effect of heme ring oxygenation on enzyme structure and function has been examined in a reconstituted cytochrome c peroxidase. Oxochlorin derivatives were formed by OsO(4) treatment of mesoporphyrin followed by acid-catalyzed pinacol rearrangement. The northern oxochlorin isomers were isolated by chromatography, and the regio-isomers assignments determined by 2D COSY and NOE 1H NMR. The major isomer, 4-mesoporphyrinone (Mp), was metallated with FeCl(2) and reconstituted into cytochrome c peroxidase (CcP) forming a hybrid green protein, MpCcP. The heme-altered enzyme has 99% wild-type peroxidase activity with cytochrome c. EPR spectroscopy of MpCcP intermediate compound I verifies the formation of the Trp(191) radical similar to wild-type CcP in the reaction cycle. Peroxidase activity with small molecules is varied: guaiacol turnover increases approximately five-fold while that with ferrocyanide is approximately 85% of native. The electron-withdrawing oxo-substitutents on the cofactor cause a approximately 60-mV increase in Fe(III)/Fe(II) reduction potential. The present investigation represents the first structural characterization of an oxochlorin protein with X-ray intensity data collected to 1.70 A. Although a mixture of R- and S-mesopone isomers of the FeMP cofactor was used during heme incorporation into the apo-protein, only the S-isomer is found in the crystallized protein. 相似文献
902.
Li XH Zhang P Wang MX Zhou F Malik FA Yang HJ Bhaskar R Hu JB Sun CG Miao YG 《Molecular biology reports》2011,38(6):3897-3902
Endoglucanase is a part of cellulase which hydrolyzes cellulose into glucose. In this study, we cloned endoglucanase III (EG
III) gene from Trichoderma viride strain AS 3.3711 using a PCR-based exon splicing method, and expressed EG III recombinant protein in both silkworm BmN cell
line and silkworm larvae with an improved Bac-to-Bac/BmNPV mutant baculovirus expression system, which lacks the chiA and v-cath genes of Bombyx mori nucleopolyhedrovirus (BmNPV). The result showed that around 45 kDa protein was visualized in BmN cells at 48 h after the
second generation recombinant mBacmid/BmNPV/EG III baculovirus infection. The enzymes from recombinant baculoviruses infected
silkworms exhibited significant maximum enzyme activity at the environmental condition of pH 8.0 and temperature 50°C, and
increased 20.94 and 19.13% compared with that from blank mBacmid/BmNPV baculoviruses infected silkworms and normal silkworms,
respectively. It was stable at pH range from 5.0 to 9.0 and at temperature range from 40 to 60°C. It provided a possibility
to generate transgenic silkworms expressing bio-active cellulase, which can catabolize dietary fibers more efficiently, and
it might be of great significance for sericulture industry. 相似文献
903.
Among the 13 TLRs in the vertebrate systems, only TLR4 utilizes both Myeloid differentiation factor 88 (MyD88) and Toll/Interleukin-1 receptor (TIR)-domain-containing adapter interferon-β-inducing Factor (TRIF) adaptors to transduce signals triggering host-protective immune responses. Earlier studies on the pathway combined various experimental data in the form of one comprehensive map of TLR signaling. But in the absence of adequate kinetic parameters quantitative mathematical models that reveal emerging systems level properties and dynamic inter-regulation among the kinases/phosphatases of the TLR4 network are not yet available. So, here we used reaction stoichiometry-based and parameter independent logical modeling formalism to build the TLR4 signaling network model that captured the feedback regulations, interdependencies between signaling kinases and phosphatases and the outcome of simulated infections. The analyses of the TLR4 signaling network revealed 360 feedback loops, 157 negative and 203 positive; of which, 334 loops had the phosphatase PP1 as an essential component. The network elements'' interdependency (positive or negative dependencies) in perturbation conditions such as the phosphatase knockout conditions revealed interdependencies between the dual-specific phosphatases MKP-1 and MKP-3 and the kinases in MAPK modules and the role of PP2A in the auto-regulation of Calmodulin kinase-II. Our simulations under the specific kinase or phosphatase gene-deficiency or inhibition conditions corroborated with several previously reported experimental data. The simulations to mimic Yersinia pestis and E. coli infections identified the key perturbation in the network and potential drug targets. Thus, our analyses of TLR4 signaling highlights the role of phosphatases as key regulatory factors in determining the global interdependencies among the network elements; uncovers novel signaling connections; identifies potential drug targets for infections. 相似文献
904.
905.
Bhaskar C. Harinath 《Journal of biosciences》1984,6(5):691-699
The immunodiagnosis of bancroftian filariasis is a major challenge to the immunoparasitologist. Significant progress is yet
to be made in developing convenient laboratory animal model and inin vitro cultivation of filarial parasites making it very difficult to obtain required amount of parasite material for research. Parasitological
examination techniques are not useful in low microfilaraemia, occult or chronic.filarial infections. A precise and accurate
immunodiagnostic technique is very much needed for successful filaria control programmes. Such a test will also avoid the
need for laborious night blood examination in bancroftian filariasis.
Due to comparatively easy availability, a good amount of work has been done to explore immunodiagnostic potential of heterologous
filarial antigens isolated fromLitomosoide carinii, Dirofilaria immitis, Brugia malayi, Setaria digitata, Setaria cervi and number of other filarial species. However, there has been limited or no significant success due to number of false negative
and false positive reactions.
Extensive study has also been made with antigens isolated fromWuchereria bancrofti microfilariae. Soluble antigens of microfilariae have been used in different immunological techniques such as skin test,
counter immuno electrophoresis, indirect haemagglutination test, indirect fluorescent antibody test and enzyme linked immunosorbent
assay. Fractionation of
Wuchereria bancrofti microfilarial soluble antigens yielded mfS3e antigen fraction which was found to be highly reactive in microfilaraemia by
enzyme linked immunosorbent assay, but the yield of the purified antigen was not sufficient enough to make it a practical
proposition for large scale isolation of antigen.
Wuchereria bancrofti microfilarial excretory-secretory antigens were found to be specific and highly sensitive requiring as little as 0.35 ng
antigen protein per well in penicillinase enzyme linked immunosorbent assay for detection of filarial antibody. One ml of
culture fluid was found to be sufficient for 400,000 tests. Field evaluation of this test showed that it can replace laborious
night blood examination.
Assay systems have been developed for detection of filarial antigen in serum, urine, hydrocele fluid and immune complexes
using immunoglobulins from chronic filarial sera and antisera to excretory filarial antigens. Further purification of excretory-secretory
antigens by affinity chromatography and production of monoclonal antibodies should hopefully give suitable reagents for use
in sensitive assays such as enzyme immuno assay and immuno radiometric assay, providing an ideal assay system for detection
of active filarial infection in the not too distant future. 相似文献
906.
Hydrogen bonding of secondary amides 总被引:1,自引:0,他引:1
907.
Bhaskar Bhattacharya 《Biometrical journal. Biometrische Zeitschrift》1996,38(7):791-808
We consider a two-factor experiment in which the factors have the same number of levels with a natural ordering among levels. We test the hypothesis that the effects of the two treatments are symmetric against a one-sided alternative using the likelihood ratio criteria. Test of the one-sided alternative as a null hypothesis against no restriction has also been studied. Exact distribution theory under the null hypothesis is derived and is shown to be a weighted mixture of chi-square distributions. An example is used to illustrate the procedure. 相似文献
908.
This paper aims to enthuse mathematicians, especially topologists, knot theorists and geometers to examine problems in the study of proteins. We have highlighted those advances and breakthroughs in knot theory that directly and indirectly help in understanding proteins. We have discussed the phenomena of knotting of protein backbone. This paper also provides a few open questions for knot theorists, the answers to which will help in further understanding of proteins. 相似文献
909.
910.