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1.
C R Groom J Thillet A C North R Pictet A J Geddes 《The Journal of biological chemistry》1991,266(30):19890-19893
Previous crystallographic studies of the antibacterial trimethoprim in complexes with bacterial and avian dihydrofolate reductases have shown substantial differences in the mode of binding, providing plausible explanations for the origin of the remarkable species selectivity of this inhibitor (Matthews, D. A., Bolin, J. T., Burridge, J. M., Filman, D. J., Volz, K. W., Kaufman, B. T., Beddell, C. R., Champness, J. N., Stammers, D. K., and Kraut, J. (1985) J. Biol. Chem. 260, 381-391; Matthews, D. A., Bolin, J. T., Burridge, J. M., Filman, D. J., Volz, K. W., and Kraut, J. (1985) J. Biol. Chem. 260, 392-399). A major species difference between the active sites is that the only carboxylate present is always Glu in vertebrates and Asp in bacteria. Crystallographic studies of the wild-type and E30D mutant of the enzyme from mouse now reveal that in both cases trimethoprim is bound in an identical fashion to that observed with the bacterial enzyme, and there is no obvious single explanation for the origin of the 10(5)-fold selectivity of trimethoprim binding. In an earlier study of a mouse wild-type enzyme using more limited data it was proposed that trimethoprim bound in the avian mode (Stammers, D. K., Champness, J. N., Beddell, C. R., Dann, J. G., Eliopoulos, E. E., Geddes, A. J., Ogg, D., and North, A. C. T. (1987) FEBS Lett. 218, 178-184), but a re-examination indicates that the occupancy of the active site by trimethoprim is less than had been thought, and we are currently unable to make an unambiguous interpretation of the electron density maps and cannot confirm the avian mode of binding in those crystals. 相似文献
2.
Fourteen new species of palms (Arecaceae) from Madagascar are described and named, based on material collected over the last
15 years. Twelve species belong to the genus Dypsis, namely D. andilamenensis Rakotoarin. & J. Dransf., D. anjae Rakotoarin. & J. Dransf., D. betsimisarakae Rakotoarin. & J. Dransf., D. culminis Rakotoarin. & J. Dransf., D. dracaenoides Rakotoarin. & J. Dransf., D. gautieri Rakotoarin. & J. Dransf., D. gronophyllum Rakotoarin. & J. Dransf., D. jeremiei Rakotoarin. & J. Dransf., D. metallica Rakotoarin. & J. Dransf., D. reflexa Rakotoarin. & J. Dransf., D. sancta Rakotoarin. & J. Dransf. and D. vonitrandambo Rakotoarin. & J. Dransf. and two species belong to the genus Ravenea: R. beentjei Rakotoarin. & J. Dransf. and R. hypoleuca Rakotoarin. & J. Dransf. Despite the fact that most of these species have been recorded from protected areas that are difficult
to access in the eastern region of Madagasacar, they are all threatened. Based on IUCN categories and criteria, seven are
Critically Endangered and seven are Vulnerable. 相似文献
3.
Correia C Monzani E Moura I Lampreia J Moura JJ 《Biochemical and biophysical research communications》1999,256(2):367-371
Tetraheme cytochrome c3 (13 kDa) and flavodoxin (16 kDa), are small electron transfer proteins that have been used to mimic, in vitro, part of the electron-transfer chain that operates between substract electron donors and respiratory electron acceptors partners in Desulfovibrio species (Palma, N., Moura, I., LeGall, J., Van Beeumen, J., Wampler, J., Moura, J. J. G. (1994) Biochemistry 33, 6394-6407). The electron transfer between these two proteins is believed to occur through the formation of a specific complex where electrostatic interaction is the main driving force (Stewart, D., LeGall, J., Moura, I., Moura, J.J.G., Peck, H.D., Xavier, A.V., Weiner, P.K. and Wampler, J.E. (1988) Biochemistry 27, 2444-2450, Stewart, D., LeGall, J., Moura, I., Moura, J.J.G., Peck, H.D., Xavier, A.V., Weiner, P., Wampler, J. (1989) Eur. J. Biochem. 185, 695-700). In order to obtain structural information of the pre-complex, a covalent complex between the two proteins was prepared. A water-soluble carbodiimide [EDC (1-ethyl-3(3 dimethylaminopropyl) carbodiimide hydrochloride] was used for the cross linking reaction. The reaction was optimized varying a wide number of experimental parameters such as ionic strength, protein and cross linker concentration, and utilization of different cross linkers and reaction time between the crosslinker and proteins. 相似文献
4.
5.
《The New phytologist》1936,35(1):94-100
Books Review in this article:
Forest Trees and Timbers of the British Empire. Part I. Some East African Coniferae and Leguminosae. By L. C halk , M.A., D.Phil., J. B urtt D avy , M.A., Ph.D. and H. E. D esch , B.SC.
Part II. Twenty West African Timber Trees. By L. C halk , M.A., D.Phil., J. B urtt D avy , M.A., Ph.D., H. E. D esch , B.SC, M.A. and A. C. H oyle , B.Sc, M.A.
Part III. Fifteen South African High Forest Timber Trees. By L. C halk , M.A., D.Phil., M. M. C hattaway , B.SC, M.A., J. B urtt D avy , M.A., Ph.D., F. S. L aughton , B.SC. and M. H. S cott , B.SC.
Colloids in Agriculture. By C. E. M arshall .
Flore Laurentienne. By F rère M arie -V ictorin , D.SC.
Plant Viruses. By K enneth M. S mith .
Plant Life: A Text-book of Botany. By D. B. S wingle .
Gardening in East Africa: A Practical Handbook. Edited by A. J. J ex -B lake , with a foreword by Sir A rthur W. H ill .
British Stem- and Leaf-Fungi (Coelomycetes). Vol. I. Sphaeropsidales. By W. B. G rove , M.A. 相似文献
Forest Trees and Timbers of the British Empire. Part I. Some East African Coniferae and Leguminosae. By L. C halk , M.A., D.Phil., J. B urtt D avy , M.A., Ph.D. and H. E. D esch , B.SC.
Part II. Twenty West African Timber Trees. By L. C halk , M.A., D.Phil., J. B urtt D avy , M.A., Ph.D., H. E. D esch , B.SC, M.A. and A. C. H oyle , B.Sc, M.A.
Part III. Fifteen South African High Forest Timber Trees. By L. C halk , M.A., D.Phil., M. M. C hattaway , B.SC, M.A., J. B urtt D avy , M.A., Ph.D., F. S. L aughton , B.SC. and M. H. S cott , B.SC.
Colloids in Agriculture. By C. E. M arshall .
Flore Laurentienne. By F rère M arie -V ictorin , D.SC.
Plant Viruses. By K enneth M. S mith .
Plant Life: A Text-book of Botany. By D. B. S wingle .
Gardening in East Africa: A Practical Handbook. Edited by A. J. J ex -B lake , with a foreword by Sir A rthur W. H ill .
British Stem- and Leaf-Fungi (Coelomycetes). Vol. I. Sphaeropsidales. By W. B. G rove , M.A. 相似文献
6.
Chao Bai Sol M. Rivera Vicente Medina Rui Alves Ester Vilaprinyo Albert Sorribas Ramon Canela Teresa Capell Gerhard Sandmann Paul Christou Changfu Zhu 《The Plant journal : for cell and molecular biology》2014,77(3):464-475
We have developed an assay based on rice embryogenic callus for rapid functional characterization of metabolic genes. We validated the assay using a selection of well‐characterized genes with known functions in the carotenoid biosynthesis pathway, allowing rapid visual screening of callus phenotypes based on tissue color. We then used the system to identify the functions of two uncharacterized genes: a chemically synthesized β–carotene ketolase gene optimized for maize codon usage, and a wild‐type Arabidopsis thaliana ortholog of the cauliflower Orange gene. In contrast to previous reports (Lopez, A.B., Van Eck, J., Conlin, B.J., Paolillo, D.J., O'Neill, J. and Li, L. ( 2008 ) J. Exp. Bot. 59, 213–223; Lu, S., Van Eck, J., Zhou, X., Lopez, A.B., O'Halloran, D.M., Cosman, K.M., Conlin, B.J., Paolillo, D.J., Garvin, D.F., Vrebalov, J., Kochian, L.V., Küpper, H., Earle, E.D., Cao, J. and Li, L. ( 2006 ) Plant Cell 18, 3594–3605), we found that the wild‐type Orange allele was sufficient to induce chromoplast differentiation. We also found that chromoplast differentiation was induced by increasing the availability of precursors and thus driving flux through the pathway, even in the absence of Orange. Remarkably, we found that diverse endosperm‐specific promoters were highly active in rice callus despite their restricted activity in mature plants. Our callus system provides a unique opportunity to predict the effect of metabolic engineering in complex pathways, and provides a starting point for quantitative modeling and the rational design of engineering strategies using synthetic biology. We discuss the impact of our data on analysis and engineering of the carotenoid biosynthesis pathway. 相似文献
7.
McLaughlin LA Paine MJ Kemp CA Maréchal JD Flanagan JU Ward CJ Sutcliffe MJ Roberts GC Wolf CR 《The Journal of biological chemistry》2005,280(46):38617-38624
We have previously shown that Phe(120), Glu(216), and Asp(301) in the active site of cytochrome P450 2D6 (CYP2D6) play a key role in substrate recognition by this important drug-metabolizing enzyme (Paine, M. J., McLaughlin, L. A., Flanagan, J. U., Kemp, C. A., Sutcliffe, M. J., Roberts, G. C., and Wolf, C. R. (2003) J. Biol. Chem. 278, 4021-4027 and Flanagan, J. U., Maréchal, J.-D., Ward, R., Kemp, C. A., McLaughlin, L. A., Sutcliffe, M. J., Roberts, G. C., Paine, M. J., and Wolf, C. R. (2004) Biochem. J. 380, 353-360). We have now examined the effect of mutations of these residues on interactions of the enzyme with the prototypical CYP2D6 inhibitor, quinidine. Abolition of the negative charge at either or both residues 216 and 301 decreased quinidine inhibition of bufuralol 1'-hydroxylation and dextromethorphan O-demethylation by at least 100-fold. The apparent dissociation constants (K(d)) for quinidine binding to the wild-type enzyme and the E216D and D301E mutants were 0.25-0.50 microm. The amide substitution of Glu(216) or Asp(301) resulted in 30-64-fold increases in the K(d) for quinidine. The double mutant E216Q/D301Q showed the largest decrease in quinidine affinity, with a K(d) of 65 microm. Alanine substitution of Phe(120), Phe(481),or Phe(483) had only a minor effect on the inhibition of bufuralol 1'-hydroxylation and dextromethorphan O-demethylation and on binding. In contrast to the wild-type enzyme, a number of the mutants studied were found to be able to metabolize quinidine. E216F produced O-demethylated quinidine, and F120A and E216Q/D301Q produced both O-demethylated quinidine and 3-hydroxyquinidine metabolites. Homology modeling and molecular docking were used to predict the modes of quinidine binding to the wild-type and mutant enzymes; these were able to rationalize the experimental observations. 相似文献
8.
The phylogenetic problem of Huia (Amphibia: Ranidae) 总被引:1,自引:0,他引:1
Stuart BL 《Molecular phylogenetics and evolution》2008,46(1):49-60
A taxonomic consensus for the diverse and pan-global frog family Ranidae is lacking. A recently proposed classification of living amphibians [Frost, D.R., Grant, T., Faivovich, J., Bain, R. H., Haas, A., Haddad, C.F.B., de Sá, R.O., Channing, A., Wilkinson, M., Donnellan, S.C., Raxworthy, C.J., Campbell, J.A., Blotto, B.L., Moler, P., Drewes, R.C., Nussbaum, R.A., Lynch, J.D., Green, D.M., Wheeler, W.C., 2006. The amphibian tree of life. B. Am. Mus. Nat. Hist. 297, 1-370] included expansion of the Southeast Asian ranid frog genus Huia from seven to 47 species, but without having studied the type species of Huia. This study tested the monophyly of this concept of Huia by sampling the type species and putative members of Huia. Molecular phylogenetic analyses consistently recovered the type species H. cavitympanum as the sister taxon to other Bornean-endemic species in the genus Meristogenys, rendering all previously published concepts of Huia as polyphyletic. Members of Huia sensu [Frost, D.R., Grant, T., Faivovich, J., Bain, R. H., Haas, A., Haddad, C.F.B., de Sá, R.O., Channing, A., Wilkinson, M., Donnellan, S.C., Raxworthy, C.J., Campbell, J.A., Blotto, B.L., Moler, P., Drewes, R.C., Nussbaum, R.A., Lynch, J.D., Green, D.M., Wheeler, W.C., 2006. The amphibian tree of life. B. Am. Mus. Nat. Hist. 297, 1-370.] appear in four places within the family Ranidae. A clade containing the type species of Odorrana is phylogenetically unrelated to the type species of Huia, and Odorrana is removed from synonymy with Huia. These findings underscore the need to include relevant type species in phylogenetic studies before proposing sweeping taxonomic changes. The molecular phylogenetic analyses revealed a high degree of homoplasy in larval and adult morphology of Asian ranid frogs. Detailed studies are needed to identify morphological synapomorphies that unite members in these major clades of ranid frogs. 相似文献
9.
Castonguay LA Treasurywala AM Caulfield TJ Jaeger EP Kellar KE 《Bioconjugate chemistry》1999,10(6):958-964
For gadolinium chelates, we determined that there is a linear correlation between calculated solvent-accessible surface area and q-value, the number of rapidly exchanging water molecules directly bound to the gadolinium ion. A calibration curve was developed to predict q-value based on the solvent-accessible surface area of gadolinium. This predictive method was validated with the following gadolinium crystal structures: (ethylenediaminetetraacetic acid)-gadolinium(III) [Gd(EDTA)] [Templeton, L. K., Templeton, D. H., Zalkin, A., and Ruben, H. W. (1982) Anomalous Scattering by Praseodymium, Samarium, and Gadolinium and Structures of their Thylenediaminetetraacetate (EDTA) Salts. Acta Crystallogr., Sect. B 38, 2155], (1,4,7,10-tetraazacyclododecane-N,N',N' ',N' "-tetraacetic acid)-gadolinium(III) [Gd(DOTA)] [Dubost, J.-P., Leger, J.-M., Langlois, M.-H., Meyer, D., and Schaefer, M. (1991) Structure of a Magnetic Resonance Imaging Agent - The Gadolinium-DOTA Complex C(16)H(24)N(4)O(8)NaGd, 5H(2)O. C. R. Acad. Sci., Ser. 2 312, 349], (diethylenetriaminepentaacetic acid)-gadolinium(III) [Gd(DTPA)] [Stezowski, J. J., and Hoard, J. L. (1984) Heavy Metal Ionophores - Correlations Among Structural Parameters of Complexed Nonpeptide Polyamino Acids. Isr. J. Chem. 24, 323], (diethylenepenta-acetato)-gadolinium(III) [Gd(DTPA-BEA)] [Smith, P. H., Brainard, J. R., Morris, D. E., Jarvinen, G. D., and Ryan, R. R. (1989) Solution and Solid-State Characterization of Europium and Gadolinium Schiff-Base Complexes and Assessment of their Potential as Contrast Agents in Magnetic Resonance Imaging. J. Am. Chem. Soc. 111, 7437], and (1,7,13-triaza-4,10, 16-trioxacyclo-octadecane-N,N',N' '-triacetato)-gadolinium(III) [Gd(TTTA)] [Chen, D., Squattrito, P. J., Martell, A. E., and Clearfield, A. (1990) Synthesis and Crystal Structure of a 9-Coordinate Gadolinium(III) Complex of 1,7,13-Triaza-4,10, 16-Trioxacyclooctadecane-N,N',N' '-Tri-Acetic Acid. Inorg. Chem. 29, 4366]. Predicted q-values were in complete agreement with experimentally determined q-values. A genetic algorithm-based conformational search method was developed to generate valid 3D models for gadolinium chelates. The method was successfully tested on the following gadolinium chelates: Gd(EDTA) (Templeton et al., 1982), Gd(DOTA) (Dubost et al., 1991), Gd(DTPA-BEA) (Smith et al., 1989), Gd(TTTA) (Chen et al., 1990), Gd(triethylene glycol) [Rogers, R. D., Voss, E. J., and Etzenhouser, R. D. (1988) F-Element Crown Ether Complexes. 17. Synthetic and Structural Survey of Lanthanide Chloride Tiethylene Glycol Complexes. Inorg. Chem. 27, 533], and Gd(tetraethylene glycol) [Rogers, R. D., Etzenhouser, R. D., Murdoch, J. S., and Reyes, E. (1991) Macrocycle Complexation Chemistry. 35. Survey of the Complexation of the Open-Chain 15-Crown-5 Analogue tetraethylene Glycol with the Lanthanide Chlorides. Inorg. Chem. 30, 1445]. 相似文献
10.
W J Fairbrother A G Palmer M Rance J Reizer M H Saier P E Wright 《Biochemistry》1992,31(18):4413-4425
Nearly complete assignment of the aliphatic 1H and 13C resonances of the IIAglc domain of Bacillus subtilis has been achieved using a combination of double- and triple-resonance three-dimensional (3D) NMR experiments. A constant-time 3D triple-resonance HCA(CO)N experiment, which correlates the 1H alpha and 13C alpha chemical shifts of one residue with the amide 15N chemical shift of the following residue, was used to obtain sequence-specific assignments of the 13C alpha resonances. The 1H alpha and amide 15N chemical shifts had been sequentially assigned previously using principally 3D 1H-15N NOESY-HMQC and TOCSY-HMQC experiments [Fairbrother, W. J., Cavanagh, J., Dyson, H. J., Palmer, A. G., III, Sutrina, S. L., Reizer, J., Saier, M. H., Jr., & Wright, P. E. (1991) Biochemistry 30, 6896-6907]. The side-chain spin systems were identified using 3D HCCH-COSY and HCCH-TOCSY spectra and were assigned sequentially on the basis of their 1H alpha and 13C alpha chemical shifts. The 3D HCCH and HCA(CO)N experiments rely on large heteronuclear one-bond J couplings for coherence transfers and therefore offer a considerable advantage over conventional 1H-1H correlation experiments that rely on 1H-1H 3J couplings, which, for proteins the size of IIAglc (17.4 kDa), may be significantly smaller than the 1H line widths. The assignments reported herein are essential for the determination of the high-resolution solution structure of the IIAglc domain of B. subtilis using 3D and 4D heteronuclear edited NOESY experiments; these assignments have been used to analyze 3D 1H-15N NOESY-HMQC and 1H-13C NOESY-HSQC spectra and calculate a low-resolution structure [Fairbrother, W. J., Gippert, G. P., Reizer, J., Saier, M. H., Jr., & Wright, P. E. (1992) FEBS Lett. 296, 148-152]. 相似文献
11.
Neocarzinostatin (NCS) is an antitumor protein from Streptomyces carzinostaticus that is identical in apo-protein sequence with mitomalcin (MMC) from Streptomyces malayensis. We describe the use of apo-NCS as a model system for applying combined two- and three-dimensional (2D and 3D) proton NMR spectroscopy to the structure determination of proteins (Mr greater than 10K) without isotope labeling. Strategies aimed at accurately assigning overlapped 2D cross-peaks by using semiautomated combined 2D and 3D data analysis are developed. Using this approach, we have assigned 99% of the protons, including those of the side chains, and identified about 1270 intra- and interresidue proton-proton interactions (fixed distances are not included) in apo-NCS. Comparing our results with those reported recently on 2D NMR studies of apo-NCS [Adjadj, E., Mispelter, J., Quiniou, E., Dimicoli, J.-L., Favadon, V., & Lhoste, J.-M. (1990) Eur. J. Biochem. 190, 263-271; Remerowski M. L., Glaser, S. J., Sieker, L., Samy, T. S. A., & Drobny, G. P. (1990) Biochemistry 29, 8401-8409] demonstrated advantages of proton 3D NMR spectroscopy in protein spectral assignments. We are able to obtain more complete proton resonance and secondary structural assignments and find several misassignments in the earlier report. Strategies utilized in this work should be useful for developing automation procedures for spectral assignments. 相似文献
12.
We previously reported wide variability in UV-B tolerance among different Metarhizium anisopliae isolates [Braga, G.U.L., Flint, S.D., Miller, C.D., Anderson, A.J., Roberts, D.W., 2001a. Variability in response to UV-B among species and strains of Metarhizium isolated from sites at latitudes from 61 degrees N to 54 degrees S. J. Invertebr. Pathol. 78, 98-108] as well as wide phenotypic variability in some of these isolates in response to alterations in their growth environments [Rangel, D.E.N., Braga, G.U.L., Flint, S.D., Anderson, A.J., Roberts, D.W., 2004. Variations in UV-B tolerance and germination speed of M. anisopliae conidia produced on artificial and natural substrates. J. Invertebr. Pathol. 87, 77-83]. Studies on other biological systems have demonstrated that strong selective pressure for tolerance to a stress factor may reduce the phenotypic variability of this trait. In the present study, conidia of the isolate most tolerant to radiation and heat, ARSEF 324, presented very little phenotypic variability in UV-B tolerance in response to production on either artificial culture medium or infected insects. The phenotypic plasticities in two other traits (conidial morphology and germination speed), however, were considerably higher. 相似文献
13.
《Biometrics》2002,58(4):1038-1048
Books reviewed in this article:
COLES, S. An Introduction to Statistical Modeling of Extreme Values.
DOWNES, B. J., BARMUTA, L. A., FAIRWEATHER, P.G., FAITH, D. P., KEOUGH, M. J., LAKE, P. S., MAPSTONE, B. D. and QUINN, G. P. Monitoring Ecological Impacts: Concepts and Practice in Flowing Waters.
BRUNNER, E., DOMHOF, S. and LANGER, F. Nonparametric Analysis of Longitudinal Data in Factorial Experiments.
LANGE, K. Mathematical and Statistical Methods for Genetic Analysis, 3rd edition.
MILLIKEN, G. A. and JOHNSON, D. E. Analysis of Messy Data, Volume III: Analysis of Covariance.
SMITH, P. J. Analysis of Failure and Survival Data.
JONES, P. W. and SMITH, P. Stochastic Processes: An Introduction.
PERCUS, J. K. Mathematics of Genome Analysis.
ROSENBAUM, P. Observational Studies, 2nd edition.
THODE, H. C., Jr. Testing for Normality.
GLAZ, J., NAUS, J. and WALLENSTEIN, S. Scan Statistics.
TOWNEND, J. Practical Statistics for Environmental and Biological Scientists.
REDDY, M. V. Statistics for Mental Health Care Research. 相似文献
COLES, S. An Introduction to Statistical Modeling of Extreme Values.
DOWNES, B. J., BARMUTA, L. A., FAIRWEATHER, P.G., FAITH, D. P., KEOUGH, M. J., LAKE, P. S., MAPSTONE, B. D. and QUINN, G. P. Monitoring Ecological Impacts: Concepts and Practice in Flowing Waters.
BRUNNER, E., DOMHOF, S. and LANGER, F. Nonparametric Analysis of Longitudinal Data in Factorial Experiments.
LANGE, K. Mathematical and Statistical Methods for Genetic Analysis, 3rd edition.
MILLIKEN, G. A. and JOHNSON, D. E. Analysis of Messy Data, Volume III: Analysis of Covariance.
SMITH, P. J. Analysis of Failure and Survival Data.
JONES, P. W. and SMITH, P. Stochastic Processes: An Introduction.
PERCUS, J. K. Mathematics of Genome Analysis.
ROSENBAUM, P. Observational Studies, 2nd edition.
THODE, H. C., Jr. Testing for Normality.
GLAZ, J., NAUS, J. and WALLENSTEIN, S. Scan Statistics.
TOWNEND, J. Practical Statistics for Environmental and Biological Scientists.
REDDY, M. V. Statistics for Mental Health Care Research. 相似文献
14.
Modeling the cellular basis of altered excitation-contraction coupling in heart failure 总被引:3,自引:0,他引:3
Raimond L. Winslow Jeremy Rice Saleet Jafri 《Progress in biophysics and molecular biology》1998,69(2-3):497-514
Ca transients measured in failing human ventricular myocytes exhibit reduced amplitude and slowed relaxation [Beuckelmann, D.J., Nabauer, M., Erdmann, E., 1992. Intracellular calcium handling in isolated ventricular myocytes from patients with terminal heart failure. Circulation 85, 1046-1055; Gwathmey, J.K., Copelas, L., MacKinnon, R., Schoen, F.J., Feldman, M.D., Grossman, W., Morgan, J.P., 1987. Abnormal intracellular calcium handling in myocardium from patients with end-stage heart failure. Circ. Res. 61, 70-76; Kaab, S., Nuss, H. B., Chiamvimonvat, N., O'Rourke, B., Pak, P.H., Kass, D.A., Marban, E., Tomaselli, G.F., 1996. Ionic mechanism of action potential prolongation in ventricular myocytes from dogs with pacing-induced heart failure. Circ. Res. 78(2); Li, H.G., Jones, D.L., Yee, R., Klein, G.J., 1992. Electrophysiologic substrate associated with pacing-induced hert failure in dogs: potential value of programmed stimulation in predicting sudden death. J. Am. Coll. Cardiol. 19(2), 444-449; Vermeulen, J.T., McGuire, M.A., Opthof, T., Colonel, R., Bakker, J.M.T.d., Klopping, C., Janse, M.J., 1994. Triggered activity and automaticity in ventricular trabeculae of failing human and rabbit hearts. Cardiovasc. Res. 28, 1547-1554.] and blunted frequency dependence [Davies, C.H., Davia, K., Bennett, J.G., Pepper, J.R., Poole-Wilson, P.A., Harding, S.E., 1995. Reduced contraction and altered frequency response of isolated ventricular myocytes from patients with heart failure. Circulation, 92, 2540-2549; Hasenfuss, G., Reinecke, H., Studer, R., Meyer, M., Pieske, B., Holtz, J., Holubarsch, C., Posival, H., Just, H., Drexler, H., 1994. Relation between myocardial function and expression of sarcoplasmic reticulum Ca-ATPase in failing and nonfailing human myocardium. Circ. Res. 75, 434-442; Hasenfuss, G., Reinecke, H., Studer, R., Pieske, B., Meyer, M., Drexler, H., Just, H., 1996. Calcium cycling proteins and force-frequency relationships in heart failure. Basic Res. Cardiol. 91, 17-22; Monte, F.D., O'Gara, P., Poole-Wilson, P.A., Yacoub, M., Harding, S.E., 1995. Cell geometry and contractile abnormalities of myocytes from failing human left ventricle. Cardiovasc. Res. 30, 281-290; Philips, P.J., Gwathmey, J.K., Feldman, M.D., Schoen, F.J., Grossman, W., Morgan, J.P., 1990. Post-extrasystolic potentiation and the force-frequency relationships: differential augmentation of myocardial contractility in working myocardium from patients with end-stage heart failure. J. Mol. Cell. Cardiol. 22, 99-110; Pieske, B., Hasenfuss, G., Holubarsch, C., Schwinger, R., Bohm, M., Just, H., 1992. Alterations of the force-frequency relationship in the failing human heart depend on the underlying cardiac disease. Basic Res. Cardiol. 87, 213-221.]. Analyses of protein levels in these failing hearts reveal that the SR Ca-ATPase is down-regulated on average by 50% and that the Na/Ca exchanger is up-regulated on average by a factor of two. In this paper, we test the hypothesis that this altered pattern of expression of Ca handling proteins is sufficient to account for changes in excitation-contraction coupling properties measured experimentally at the cellular level. To do this, we present an integrated model of excitation-contraction coupling in the guinea pig ventricular cell. The model is used to determine the effects of SR Ca-ATPase down-regulation and Na/Ca exchanger up-regulation on action potential duration, Ca transient shape and amplitude, and isometric force. Model analyses demonstrate that changes in Ca handling proteins play a direct and critical role in prolongation of action potential duration, and in reduction of contractile force in heart failure. 相似文献
15.
Mode of action and substrate specificities of cellulases from cloned bacterial genes 总被引:19,自引:0,他引:19
N R Gilkes M L Langsford D G Kilburn R C Miller R A Warren 《The Journal of biological chemistry》1984,259(16):10455-10459
Three recombinant plasmids, pEC1, pEC2, and pEC3, each containing a unique Cellulomonas fimi chromosomal DNA insert, expressed Cm-cellulase activities in Escherichia coli C600 (Whittle, D. J., Kilburn, D. H., Warren, R. A. J., and Miller, R. C., Jr. (1982) Gene (Amst.) 17, 139-145; Gilkes, N. R., Kilburn, D. G., Langsford, M. L., Miller, R. C., Jr., Wakarchuk, W. W., Warren, R. A. J., Whittle, D. J., and Wong, W. K. R. (1984) J. Gen. Microbiol. 130, 1377-1384). Viscometric and chemical analyses showed that the enzymes encoded by pEC2 and pEC3 behaved as endoglucanases, whereas that encoded by pEC1 behaved as an exoglucanase. The activities of the exoglucanase and the pEC2-encoded endodglucanase were additive on Cm-cellulose as substrate. The pEC1-encoded enzyme also hydrolyzed xylan and p-nitrophenyl cellobioside. Two substrate-bound Cm-cellulases were isolated from the residual cellulose in a C. fimi culture by guanidine hydrochloride elution, affinity chromatography, and polyacrylamide gel electrophoresis. Both were glycoproteins of apparent Mr = 58,000 and 56,000, respectively. The 56-kDa enzyme appeared to be identical with the pEC1-encoded product, suggesting that they arise from the same gene. 相似文献
16.
A Bouhss S Dementin C Parquet D Mengin-Lecreulx J A Bertrand D Le Beller O Dideberg J van Heijenoort D Blanot 《Biochemistry》1999,38(38):12240-12247
To evaluate their role in the active site of the UDP-N-acetylmuramoyl-L-alanine:D-glutamate ligase (MurD) from Escherichia coli, 12 residues conserved either in the Mur superfamily [Eveland, S. S., Pompliano, D. L., and Anderson, M. S. (1997) Biochemistry 36, 6223-6229; Bouhss, A., Mengin-Lecreulx, D., Blanot, D., van Heijenoort, J., and Parquet, C. (1997) Biochemistry 36, 11556-11563] or in the sequences of 26 MurD orthologs were submitted to site-directed mutagenesis. All these residues lay within the cleft of the active site of MurD as defined by its 3D structure [Bertrand, J. A., Auger, D., Fanchon, E., Martin, L., Blanot, D., van Heijenoort, J., and Dideberg, O. (1997) EMBO J. 16, 3416-3425]. Fourteen mutant proteins (D35A, K115A, E157A/K, H183A, Y194F, K198A/F, N268A, N271A, H301A, R302A, D317A, and R425A) containing a C-terminal (His)(6) extension were prepared and their steady-state kinetic parameters determined. All had a reduced enzymatic activity, which in many cases was very low, but no mutation led to a total loss of activity. Examination of the specificity constants k(cat)/K(m) for the three MurD substrates indicated that most mutations affected both the binding of one substrate and the catalytic process. These kinetic results correlated with the assigned function of the residues based on the X-ray structures. 相似文献
17.
《Ibis》1994,136(3):377-391
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Z immerman , J.L. 相似文献
B aker . K. 1993. Identification Guide to European Non-passerines.
B arnard . C., G ilbert , F. & M c G regor
B askett , T.S., S ayre . M.W., T omlinson , R.E. & M irarchi .
B ezzel . E. 1993. Kompendium der Vögel Mitteleuropas.
B right , M. 1993. The Private Life of Birds.
C ook , M. 1992. The Birds of Moray and Nairn.
D avison . G.W.H. 1992. Birds of Mount Kinabalu. Borneo.
E rritzoe . J. 1993. The Buds of CITES and How to Identify Them.
F arner , D.S., K ing , J.R. & P arkes , K.C.
G ibbons , D.W., R eid , J.B. & C hapman . R.A. (eds). 1993. The New Atlas of Breeding Birds in Britain and Ireland.
H illman , J.C.
H uxley . E.
J ackson . C.E. 1993. Great Bird Paintings of the World.
J ohnsgard . P.A. 1993. Cormorants, Darters and Pelicans of the World.
M adge . S. & B urn , H. 1994. Crows and Jays. A Guide to the Crows, Jays and Magpies of the World.
N icolai . B. (ed.).
P ower , D.M. (ed.).
P riklonskiy . S.G. (ed.).
R alph . R. 1993. William MacGillivray.
R obinson , D. & C hapman , A.
S harp . P.J. 1993. Avian Endocrinology.
S mith , K.W., D fe , C.W., F earnside . J.D., F letcher , E.W. & S mith , R.N.
S olomon . D. & W illiams , J.
S ørensen , S., B loch . D. & L angvad . S.
Z immerman , J.L. 相似文献
18.
19.
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M. S. Ridout 《Biometrics》2001,57(2):644-658
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KARIAN, Z. A. and DUDEWICZ, E. J. Fitting Statistical Distributions: The Generalized Lambda Distribution and Generalized Bootstrap Methods. 相似文献
BERNARDO, J. M., BERGER, J. O., DAWID, A. P., and SMITH, A. F. M. (editors). Bayesian Statistics 6.
VAN DER VAART, A. W. Asymptotic Statistics.
NOLAN, D. and SPEED, T. StatLabs: Mathematical Statistics Through Applications.
BINNS, M. R., NYROP, J. P., and VAN DER WERF, W. Sampling and Monitoring in Crop Protection: The Theoretical Basis for Developing Practical Decision Guides.
DIECKMANN, U., LAW, R., and METZ, J. A. J. (editors). The Geometry of Ecological Interactions: Simplifying Spatial Complexity.
LAWSON, A., BIGGERI, A., BOHNING, D., LESAFFRE, E., VIEL, 3.-F., and BERTOLLINI, R. Disease Mapping and Risk Assessment for Public Health.
BLAND, M. and PEACOCK, J. Statistical Questions in Evidence Based Medicine. Oxford University Press, Oxford, 2000.
MANLY, B. F. J. Statistics for Environmental Science and Management.
RÍOS INSUA, D. and RUGGERI, F. (editors) Robust Bayesian Analysis.
BARNDORFF-NIELSEN, 0. E., COX, D. R., and KLUP-PELBERG, C. Complex Stochastic Systems.
PETRIE, A. and SABIN, C. Medical Statistics at a Glance.
THERNEAU, T. M. and GRAMBSCH, P. M. Modeling Survival Data: Extending the Cox Model.
TAN, W.-Y. Stochastic Modeling of AIDS Epidemiology and HIV Pathogenesis.
CHATFIELD, C. Time-Series Forecasting.
MATTHEWS, J. N. S. An Introduction to Randomized Controlled Clinical Trials.
CLARK, I. and HARPER, W. V. Practical Geostatistics 2000.
TANIGUCHI, M. and KAKIZAWA, Y. Asymptotic Theory of Statistical Inference for Time Series.
KARIAN, Z. A. and DUDEWICZ, E. J. Fitting Statistical Distributions: The Generalized Lambda Distribution and Generalized Bootstrap Methods. 相似文献