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Wang C, Huang G, Liang Z, Wu J, Xu G, Yue J, Shi Y. [Advances in the research on sources and sinks of CH4 and CH4 oxidation (uptake) in soil]. YING YONG SHENG TAI XUE BAO = THE JOURNAL OF APPLIED ECOLOGY 2002; 13:1707-12. [PMID: 12682988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Methane (CH4) is one of the main greenhouse gases contributing greenhouse effect, and its potential greenhouse effect is 21 times of CO2. Therefore, to determine the sources and sinks of atmospheric CH4 and to assess and forecast their amounts become and important focus concerning the researches on global change and greenhouse effect. This paper summarized the researches on the sources and sinks of CH4, and amplified on the influential factors (e.g. land-use, ambient atmospheric CH4 concentration, soil temperature, soil moisture content, soil pH and soil porosity) on atmospheric and interior CH4 oxidation in soil. It is significant that studying CH4 oxidation in vertical zonation soil in forests of Changbai Mountain to evaluate the CH4 consumption in forest soil.
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Xu G, Mattice WL. Energetic and Entropic Contributions to the Surface Energy of a Free-Standing Thin Film of n-Tetracontane. J Phys Chem B 2002. [DOI: 10.1021/jp021470d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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278
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Xu G, Li Y, Shi Y, Huang G. [Effect of free-air CO2 enrichment on soil microbe in paddy field]. YING YONG SHENG TAI XUE BAO = THE JOURNAL OF APPLIED ECOLOGY 2002; 13:1358-9. [PMID: 12557692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
Utilizing FACE research site in Anzhen of Wuxi, the effect of CO2 concentration increasing on soil microbe was studied in a paddy field under the condition of local cultivation, irrigation and fertilization. The results showed that soil respiration intensity was 31.88 ml.kg-1 and bacteria number was 1.51 x 10(6) ind.g-1 dry soil in FACE area, which were greater than those in control area (soil respiration intensity 27.83 ml.kg-1, bacteria number was 1.25 x 10(6) ind.g-1 dry soil, but the differences were not significant.
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279
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Xu G, Zhao L, Fuchs M. Differences between hepatic and biliary lipid metabolism and secretion in genetically gallstone-susceptible and gallstone-resistant mice. Chin Med J (Engl) 2002; 115:1292-5. [PMID: 12411097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2023] Open
Abstract
OBJECTIVE To investigate differences between hepatic and biliary lipid metabolism and secretion of genetically gallstone-susceptible (C57L) and resistant (AKR) mice and the mechanism of cholesterol gallstone formation. METHODS The inbred C57L and AKR mice were fed a lithogenic diet containing 15% fat, 1.25% cholesterol and 0.5% cholic acid for four weeks. Hepatic cholesterol content and secretion rates of biliary lipids, as well as phenotypes of the liver and gallbladder were determined and examined before and after the feeding of the lithogenic diet. RESULTS Both before and after ingestion of the lithogenic diet, hepatic secretion rates of all biliary lipids in C57L mice were markedly higher than that of AKR mice (P < 0.05, P < 0.01, respectively), whereas hepatic cholesterol contents of C57L mice were significantly lower than that of AKR mice (P < 0.05). Furthermore, after consumption of the lithogenic diet, the increase in hepatic secretion rate of biliary cholesterol in C57L mice was significantly higher than that in AKR mice (P < 0.01). Cholesterol gallstones formed in C57L mice and fatty livers developed in AKR mice. CONCLUSIONS Biliary cholesterol hypersecretion is the key pathophysiological defect of gallstone formation, lith genes have effects on biliary cholesterol hypersecretion and susceptibility to cholesterol gallstone formation in C57L mice. Lithogenic bile is formed at the canalicular membrane and precedes the development of cholesterol gallstones. It is most likely that cholesterol and bile acid hyposecretion make the AKR strain susceptible to the development of fatty livers and resistant to gallstone formation.
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280
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Xu G, Mattice WL. Monte Carlo simulation on separation and co-crystallization of a mixture of short polyethylene chains in a thin film. J Chem Phys 2002. [DOI: 10.1063/1.1492281] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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281
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282
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Xu G, Vao-soongnern V, Mattice WL. Similarities and Differences in the Rapid Crystallization Induced in n-Tetracontane by an Instantaneous Deep Quench of the Free-Standing Nanofiber and Free-Standing Thin Film. MACROMOL THEOR SIMUL 2002. [DOI: 10.1002/1521-3919(20020601)11:5<494::aid-mats494>3.0.co;2-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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283
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Xu G, Clancy TC, Mattice WL, Kumar SK. Increase in the Chemical Potential of Syndiotactic Polypropylene upon Mixing with Atactic or Isotactic Polypropylene in the Melt. Macromolecules 2002. [DOI: 10.1021/ma0119427] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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284
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Xu G, Mattice WL. Monte Carlo simulation of the crystallization and annealing of a freestanding thin film of n-tetracontane. J Chem Phys 2002. [DOI: 10.1063/1.1431587] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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285
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Xu G, Mattice WL. Simulation of the initial development of an inhomogeneous structure upon cooling an elastomeric polypropylene from a homogeneous melt. POLYMER 2002. [DOI: 10.1016/s0032-3861(02)00641-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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286
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Xu G, Mattice WL. Study on structure formation of short polyethylene chains via dynamic Monte Carlo simulation. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s1089-3156(01)00027-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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287
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Tao F, Sim WS, Xu GQ, Qiao MH. Selective binding of the cyano group in acrylonitrile adsorption on Si(100)-2 x 1. J Am Chem Soc 2001; 123:9397-403. [PMID: 11562222 DOI: 10.1021/ja010574j] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The covalent binding of acrylonitrile (CH(2)=CH-C triple bond N) and the formation of a C=C-C=N structure on Si(100) have been investigated using high-resolution electron energy loss spectroscopy (HREELS), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and density functional theory (DFT) calculations. For chemisorbed acrylonitrile, the absence of nu(C triple bond N) at 2245 cm(-1) and the appearance of nu(C=N) at 1669 cm(-1) demonstrate that the cyano group directly participates in the interaction with Si(100), which is further supported by XPS and UPS observations. Our experimental results and DFT calculations unambiguously demonstrate a [2 + 2] cycloaddition mechanism for acrylonitrile chemisorption on Si(100) through the binding of C triple bond N to Si dimers. The resulting chemisorbed monolayer with a C=C-C=N skeleton can serve as a precursor for further chemical syntheses of multilayer organic thin films in a vacuum and surface functionalization for in situ device fabrication.
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288
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Hu YF, Sham TK, Zou Z, Xu GQ, Chan L, Yates BW, Bancroft GM. A study of titanium nitride diffusion barriers between aluminum and silicon by X-ray absorption spectroscopy: the Si, Ti and N results. JOURNAL OF SYNCHROTRON RADIATION 2001; 8:860-862. [PMID: 11512957 DOI: 10.1107/s0909049500018252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2000] [Accepted: 11/22/2000] [Indexed: 05/23/2023]
Abstract
We report a multi-elment, multi-edge and multi-detection mode X-ray photoabsorption study of a series of Al/TiN(x)/Si(100) thin films as a function of the TiN(x) film thickness (100A-500A) and of the annealing temperature (400 degrees C-600 degrees C). The Si K- and L-edge results show that Si does not diffuse to the surface for all the films. The high resolution Ti L-edge and N K-edge spectra show that the TiN(x) layer undergoes a dramatic chemical reaction with the gradual increase in the annealing temperature. This chemical reaction stabilizes at 560 degrees C at which the TiN(x) film is known to fail to act as an effective diffusion barrier between Al and Si.
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289
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Li HB, Chen F, Zhang TY, Yang FQ, Xu GQ. Preparative isolation and purification of lutein from the microalga chlorella vulgaris by high-speed counter-current chromatography. J Chromatogr A 2001; 905:151-5. [PMID: 11206781 DOI: 10.1016/s0021-9673(00)00987-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
High-speed counter-current chromatography (HSCCC) was applied to the isolation and purification of lutein from microalgae. Analytical HSCCC was used for the preliminary selection of a suitable solvent system composed of n-hexane-ethanol-water (4:3:1, v/v). Using the above solvent system, preparative HSCCC was successfully performed yielding lutein at 98% purity from 200 mg of the crude extract in a one-step separation.
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Cao Y, Wang Z, Deng JF, Xu GQ. Evidence for Dangling Bond Mediated Dimerization of Furan on the Silicon (111)-(7x7) Surface This work was supported by the National University of Singapore (grant no. 3970612). Angew Chem Int Ed Engl 2000; 39:2740-2743. [PMID: 10934412 DOI: 10.1002/1521-3773(20000804)39:15<2740::aid-anie2740>3.0.co;2-j] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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291
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Xu G, Ding J, Yang Y. Monte Carlo simulation of self-avoiding lattice chains subject to simple shear flow Part II. Three-dimensional results and comparison with experiments. POLYMER 2000. [DOI: 10.1016/s0032-3861(99)00492-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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292
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Zhu J, Xu G, Ding J, Yang Y. Phase separation kinetics in mixtures of flexible polymers and low molecular weight liquid crystals. MACROMOL THEOR SIMUL 1999. [DOI: 10.1002/(sici)1521-3919(19990901)8:5<409::aid-mats409>3.0.co;2-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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293
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Zou Z, Hu YF, Sham TK, Huang HH, Xu GQ, Seet CS, Chan L. XAFS studies of Al/TiNx films on Si(100) at the Al K- and L3,2-edge. JOURNAL OF SYNCHROTRON RADIATION 1999; 6:524-525. [PMID: 15263367 DOI: 10.1107/s0909049599001247] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/1998] [Accepted: 01/22/1999] [Indexed: 05/24/2023]
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294
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Xu G, Ding J, Yang Y. Anisotropic and enhanced self-diffusion of a macromolecular chain under simple shear flow as revealed by Monte Carlo simulation on lattices. MACROMOL THEOR SIMUL 1998. [DOI: 10.1002/(sici)1521-3919(19980101)7:1<129::aid-mats129>3.0.co;2-i] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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295
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Xu G, Ding J, Yang Y. Monte Carlo simulation of self-avoiding lattice chains subject to simple shear flow. I. Model and simulation algorithm. J Chem Phys 1997. [DOI: 10.1063/1.474763] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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296
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Zhang SL, Zhou CT, Cao HK, Xu GQ. [Analysis of the clinic with pathology and detection using IGSS of 201 cases of discoid lupus erythematosus]. SHANGHAI KOU QIANG YI XUE = SHANGHAI JOURNAL OF STOMATOLOGY 1996; 5:132-4. [PMID: 15160001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Clinic pathology and detection using IGSS of 201 cases of discoid lupus erythematosus (DLE) were studied in this paper.The results showed:1.DLE usually occured on the low lip(60%);2.Suffering from gastrointestinal disease were the first symptom(25%DLE cases was confirmed by mild dysplasia,3 cases of carcinoma.1 cases Combined of DLE and lichen planus(LP);4.Immunogold-silver Staining (IGSS) was applied to detect immune complex.The result indicated that Fg,immunoglobins and complement C3 deposited at basal membrane zone of DLE.It is illustrated that DLE is an autoimmune disease which is caused by many kinds of factors and may be cancerous.Coexistence of DLE and LP suggested that they may be at different stages of the same disease.Its mechanism will be further studied.
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297
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Xu GQ, Yamano T, Shimada M. Copper distribution in fetus and placenta of the macular mutant mouse as a model of Menkes kinky hair disease. BIOLOGY OF THE NEONATE 1994; 66:302-10. [PMID: 7873696 DOI: 10.1159/000244121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Menkes kinky hair disease (MKHD) in humans is caused by a disturbance in copper homeostasis. A mutant mouse shows clinical and biochemical features very close to MKHD. In an attempt to elucidate the defect in copper transport, the copper distribution in various organs of 18-gestational-day-old macular mouse embryos, following administration by a single injection of saline (control) or 50 micrograms of CuCl2 on day 16 of gestation or by two injections on days 15 and 17 of gestation to the dams, was examined both biochemically and histochemically. The copper content in the hemizygous fetus (Ml/y) born to the homozygous mother, who had no copper injection during gestation, was lower in the brain and liver but higher in the placenta than in the respective organs of the normal fetus. When 50 micrograms of CuCl2 was injected into heterozygous dams (Ml/+) on day 16 of gestation, their hemizygous fetuses showed a slight increase in the copper content in the brain and liver, but the amount of copper in these organs was still less than that of the normal fetus. Conversely, the copper content in the placenta of the hemizygous fetus was far higher than that of the normal fetus. In the copper staining of the fetuses harvested from heterozygous dams, some fetuses showed copper deposition in the placenta, but not in the liver. The others showed no copper deposit in both the placenta and liver, thus indicating that the former were hemizygous for the mutation and the latter were normal littermates.(ABSTRACT TRUNCATED AT 250 WORDS)
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298
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Dobrowolski Z, Xu GQ, Chen W, Hitchcock-DeGregori SE. Analysis of the regulatory and structural defects of troponin C central helix mutants. Biochemistry 1991; 30:7089-96. [PMID: 1830216 DOI: 10.1021/bi00243a008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Five deletion mutants of the D/E linker region of the troponin C central helix were tested for conformational and functional differences from wild-type troponin C. The mutants were in the region 87KEDAKGKSEEE97: dEDA, dKG, dKGK, dKEDAKGK, and dSEEE, designed to change the length of the central helix and the orientation of the Ca(2+)-binding domains relative to each other [Dobrowolski, Z., Xu, G.-Q., & Hitchcock-DeGregori, S.E. (1991) J. Biol. Chem. 266, 5703-5710]. Previous work showed that all mutants except dSEEE are partially defective in one part of the Ca2+ switch or the other. All mutants undergo Ca(2+)-dependent conformational changes as detected by changes in electrophoretic mobility, alpha-helix content, and hydrophobic exposure. Deletions of the central helix do not extensively alter the thermal stability of troponin C, as determined by temperature-dependent loss of alpha-helix. There are differences among the mutants that do not correlate with function. All troponin C mutants show Ca(2+)-dependent interaction with troponin I and T in polyacrylamide gels. Troponin I-troponin C interaction was also analyzed by Ca(2+)-dependent increase in the monomer/excimer ratio of tropinin I and relief of inhibition of the actomyosin S1 ATPase. While all mutants retain basic function, dKGK, dKEDAKGK, and dEDA have altered interaction with troponin I in the absence of Ca2+. dSEEE differs in conformation from wild type, but it is normal in functional assays. This conserved region of the D/E linker is not required for interaction with troponin I in the presence or absence of urea.
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Xu GQ, Xi NZ, Chen GS, Jiang XG, Xu HN. [Effect of enhancers on cutaneous permeation of piroxicam in vitro]. ZHONGGUO YAO LI XUE BAO = ACTA PHARMACOLOGICA SINICA 1991; 12:235-8. [PMID: 1781286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Enhancing effects on the permeation of piroxicam (Pir) through excised hairless mouse (inbred HRS mice) skin were investigated by measuring flux. Azone 1% was found to be the most effective enhancer studied, increasing the flux about 21 times. The effect of Azone was enhanced by the presence of propylene glycol. Oleic acid, ethylacetate, and ethanol promoted the diffusion of Pir. Other enhancers, such as DMSO, PEG 400, acetone, urea and salicylic acid, showed little or no effect. Pir-beta-cyclodextrin inclusion compound increased the flux about 3 times. The results revealed that lipophilic enhancers were more effective than lipophobic ones.
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300
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Dobrowolski Z, Xu GQ, Hitchcock-DeGregori SE. Modified calcium-dependent regulatory function of troponin C central helix mutants. J Biol Chem 1991; 266:5703-10. [PMID: 1826002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Mutations have been made in the exposed region of the avian troponin C central helix, the D/E linker, which change its length and the orientation of the Ca2(+)-binding domains relative to each other. The region 87Glu-Asp-Ala-Lys-Gly-Lys-Ser-Glu-Glu-Glu97 has been altered in five deletion (d) mutants: dEDA, dKG, dKGK, dSEEE, and dKEDAKGK. The recombinant troponin Cs were expressed in Escherichia coli, purified, and assayed for function. All mutants retained basic troponin C function. They all bound Ca2+ to the low and high affinity sites, and they all were able to confer Ca2+ sensitivity on the regulated actomyosin ATPase. However, the regulatory function of all mutants except dSEEE was defective in one part of the Ca2+ switch or the other. In certain conditions dKGK and dKEDAKGK failed to inhibit fully whereas dEDA and dKG failed to activate the regulated actomyosin ATPase fully. The following general conclusions have been made. (a) The length of the D/E linker per se (assuming the linker is helical) and the orientation of the two Ca2(+)-binding domains relative to each other are not crucial for regulation. (b) The conserved charge cluster 95Glu-Glu-Glu97, in a region of troponin C known to bind to troponin I and postulated to be required for regulation, appears to be unimportant for function. (c) Deletion of 88Glu-Asp-Ala90 resulted in a troponin C that could not activate the actomyosin (or S1) ATPase over the level of actomyosin alone, thus defining a role for troponin C in this aspect of thin filament regulation. The results have been interpreted in terms of the crystallographic structure of troponin C and related to results with analogous calmodulin mutants.
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