351
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Levy RM, Sheridan RP, Keepers JW, Dubey GS, Swaminathan S, Karplus M. Molecular dynamics of myoglobin at 298 degrees K. Results from a 300-ps computer simulation. Biophys J 1985; 48:509-18. [PMID: 3840041 PMCID: PMC1329364 DOI: 10.1016/s0006-3495(85)83806-6] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We have carried out a very long (300 ps) molecular dynamics simulation of the protein myoglobin. This trajectory is approximately three times longer than the longest previous molecular dynamics simulation of a protein, and ten times longer than protein simulations of comparable size (1,423 atoms in our model). Here we report results from this long simulation concerning the average structure, the mean square fluctuations of atoms about the average structure, and the nuclear magnetic resonance order parameters for various groups in myoglobin. The results demonstrate that the average coordinates change very slowly during the simulation. The relative atomic mobilities are well described by the simulation. For both the mean square atomic fluctuations and the order parameters, however, there are significant quantitative differences when values calculated using shorter portions of the trajectory are compared with results obtained for the entire 300-ps simulation. The implications of this result for obtaining converged properties from protein molecular dynamics simulations for comparison with experiment are discussed.
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352
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Swaminathan S, Craven BM, McMullan RK. Alloxan – electrostatic properties of an unusual structure from X-ray and neutron diffraction. ACTA CRYSTALLOGRAPHICA SECTION B: STRUCTURAL SCIENCE 1985. [DOI: 10.1107/s0108768185001732] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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353
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Ravikumar V, Rajagopalan K, Swaminathan S. Anionic oxycope rearrangements in acetylenic spiro systems. Tetrahedron Lett 1985. [DOI: 10.1016/s0040-4039(00)95107-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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354
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Ravikumar VT, Thangaraj K, Swaminathan S, Rajagopalan K. Synthesis of A-Homo Wieland-Miescher Ketone: A Useful Building Block for Condensed Cycloheptanoid Natural Products. SYNTHESIS-STUTTGART 1985. [DOI: 10.1055/s-1985-31417] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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355
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Swaminathan S, Johnson MD, Reznikoff CA, Bryan GT. Bioconversion and macromolecular binding of 2-amino-4-(5-nitro-2-furyl)thiazole by cultured rat urothelial cells. Cancer Res 1984; 44:5511-6. [PMID: 6498813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Bioconversion and binding of 2-amino-4-(5-nitro-2-furyl)-thiazole (ANFT) were examined using cultured rat bladder epithelial cells from weanling male F344 rats. Bladder cells were obtained in large quantities from outgrowths of dissected explants which were grown on collagen gels. Metabolic potential of rat urothelial cells to activate ANFT was evaluated by incubating primary culture cells with [2-14C]ANFT for 48 hr. Metabolites were subsequently analyzed by chromatographic and spectroscopic methods. Thin-layer chromatography of the ethyl acetate:diethyl ether (1:1, v/v) extract of the culture medium revealed two regions of radioactivity with Rf values of 0.12 and 0.60, the former corresponding to ANFT and the latter to one of its metabolites. High-pressure liquid chromatography of the solvent extract revealed two major peaks, with retention times of about 4 and 9 min, corresponding with the metabolite and ANFT, respectively. Low-resolution mass spectrum of the isolated metabolite showed a molecular ion at m/e 181. The metabolite was identified as 1-[4-(2-aminothiazolyl)]-3-cyano-1-propanone based on its chromatographic and spectral characteristics in comparison with the synthetic compound. About 24% of the recovered radioactivity from the culture medium was extractable into the organic phase, a majority of which was identified as 1-[4-(2-aminothiazolyl)]-3-cyano-1-propanone. Analysis of binding to proteins and nucleic acids prepared following exposure of [2-14C]ANFT revealed a 15- and 9-fold greater amount of binding, respectively, in cultures incubated with bladder cells than their corresponding heat-inactivated controls. Furthermore, homogenates of cultured bladder cells reduced ANFT on anaerobic incubation with reduced nicotinamide adenine dinucleotide phosphate to generate 1-[4-(2-aminothiazolyl)]-3-cyano-1-propanone. On reduction of [2-14C]ANFT with rat bladder or liver homogenates, about 23 and 11%, respectively, of the initial amounts of radioactivity were bound to the trichloracetic acid-insoluble fraction. These data demonstrate that rat bladder cells possess the metabolic capability to reduce ANFT and to generate reactive intermediate(s) that bind to cellular macromolecules.
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356
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Swaminathan S, Craven BM. Electrostatic properties of phosphorylethanolamine at 123 K from crystal diffraction. ACTA CRYSTALLOGRAPHICA SECTION B: STRUCTURAL SCIENCE 1984. [DOI: 10.1107/s0108768184002573] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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357
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Weber HP, McMullan RK, Swaminathan S, Craven BM. The structure and thermal motion of phosphorylethanolamine at 122 K from neutron diffraction. ACTA CRYSTALLOGRAPHICA SECTION B: STRUCTURAL SCIENCE 1984. [DOI: 10.1107/s0108768184002561] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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358
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Craven BM, Swaminathan S, Weber HP, McMullan RK. Electrostatic properties of phosphorylethanolamine at 123 K from crystal diffraction. Acta Crystallogr A 1984. [DOI: 10.1107/s0108767384094538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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359
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Swaminathan S, Furey W, Yoo CS, Wang BC, Sax M. On the conservation of protein–solvent interactions in immunoglobulin variable domains. Acta Crystallogr A 1984. [DOI: 10.1107/s0108767384098160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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360
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Chacko KK, Ravichandran V, Swaminathan S. The conformation of proline using the concept of pseudorotation. Acta Crystallogr A 1984. [DOI: 10.1107/s0108767384096872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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361
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Swaminathan S, Craven BM, Spackman MA, Stewart RF. Theoretical and experimental studies of the charge density in urea. ACTA CRYSTALLOGRAPHICA SECTION B: STRUCTURAL SCIENCE 1984. [DOI: 10.1107/s0108768184002378] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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362
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Swaminathan S, Bryan GT. Biotransformation of the bladder carcinogen N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide in mice. Cancer Res 1984; 44:2331-8. [PMID: 6722771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The biotransformation of N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT), a potent urinary bladder carcinogen, was studied in mice. About 82% of radioactivity was excreted as 14CO2 within 36 hr after intragastric administration of N-[4-(5-nitro-2-furyl)-2-thiazolyl]-[14C]formamide, suggesting its deformylation to 2-amino-4-(5-nitro-2-furyl)thiazole ( ANFT ). The latter was formed in vitro as a product following incubation of FANFT with mouse liver homogenates. Chromatographic analysis of mouse urine obtained 24 hr after the i.p. administration of N-[4-(5-nitro-2-furyl)-[2-14C]thiazolyl]formamide revealed excretion of ANFT and unmetabolized FANFT, suggesting the prevalence of the deformylation reaction in vivo. In addition, at least two more metabolites were present in urine. One of these metabolites exhibited chromatographic properties similar to those exhibited by a compound derived from the in vitro nitroreduction of ANFT . This metabolite was isolated from urine of FANFT-fed animals and from in vitro enzymatic reduction of ANFT with mouse liver homogenates. The isolated products had chromatographic and spectral properties and a mass spectral fragmentation pattern similar to that of a compound obtained by catalytic reduction of ANFT with palladium and activated carbon. Spectroscopic analyses established the structural identity of the chemical reduction product as 1-[4-(2-aminothiazolyl)]-3-cyano-1-propanone ( ATCP ). Since the chromatographic properties of the enzymatically derived product and the urinary metabolite were identical to those of a compound obtained by chemical reduction, they must be structurally the same and thus correspond to ATCP . About 5% of the urinary metabolites of FANFT is ATCP , and thus ATCP is quantitatively a minor excretory product. ATCP was far less active than was ANFT of FANFT in the Ames mutagenicity assay with Salmonella typhimurium TA.
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363
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Swaminathan S, Craven BM, McMullan RK. The crystal structure and molecular thermal motion of urea at 12, 60 and 123 K from neutron diffraction. ACTA CRYSTALLOGRAPHICA SECTION B: STRUCTURAL SCIENCE 1984. [DOI: 10.1107/s0108768184002135] [Citation(s) in RCA: 240] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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364
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365
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Kannan R, Geetha P, Swaminathan S. An unusual reductive cyclization. Tetrahedron Lett 1984. [DOI: 10.1016/s0040-4039(01)90022-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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366
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Thangaraj K, Srinivasan PC, Swaminathan S. A New Synthesis of 3,5-Cyclodecadienones via an Acetylenic Anionic Oxy-Cope Rearrangement. SYNTHESIS-STUTTGART 1984. [DOI: 10.1055/s-1984-31053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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367
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Paul VK, Swaminathan S, Choudhary C, Choudhary VP. Letterer-Siwe disease. THE INDIAN JOURNAL OF CHEST DISEASES & ALLIED SCIENCES 1983; 25:299-301. [PMID: 6679501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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368
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Swaminathan S, Gooding LR. Inhibition of glycosylation prevents H-2K and D antigen expression on SV40 virus-transformed cells. Eur J Immunol 1983; 13:335-40. [PMID: 6303796 DOI: 10.1002/eji.1830130412] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Tunicamycin, an inhibitor of glycosylation, was used to examine the role of carbohydrate moieties of glycoproteins involved in recognition of Simian virus 40 (SV40)-transformed cells by cytotoxic T lymphocytes (CTL). Tunicamycin treatment renders such cells refractory to lysis by H-2 restricted, SV40-specific CTL as well as by allogeneic CTL directed only against H-2 antigens. Treated cells are no longer susceptible to lysis by anti-H-2 antisera and complement, nor are they stained by monoclonal anti-H-2 antibodies in an indirect immunofluorescence assay. No accumulation of H-2 proteins was detected in immunoprecipitates from cells labeled with [35S]methionine in the presence of tunicamycin. It is concluded that tunicamycin prevents the expression of H-2 glycoproteins in these cells, perhaps due to accelerated degradation of the unglycosylated molecules.
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369
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Gopalakrishnan G, Jayaraman S, Rajagopalan K, Swaminathan S. A Useful Synthesis of 1,6-Dioxo-8a-methyl-trans-Δ7-octalin: An Isomer of Wieland-Miescher Ketone. SYNTHESIS-STUTTGART 1983. [DOI: 10.1055/s-1983-30517] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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370
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Swaminathan S, Bryan GT. Deacetylation of 4-(5-acetylamino-2-furyl)thiazole and formation of 1-(4-thiazolyl)-3-cyano-1-propanone by rat liver tissues. Biochem Pharmacol 1983; 32:21-7. [PMID: 6830616 DOI: 10.1016/0006-2952(83)90646-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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371
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Karplus M, Swaminathan S, Ichiye T, Van Gunsteren WF. Local and collective motions in protein dynamics. CIBA FOUNDATION SYMPOSIUM 1983; 93:271-90. [PMID: 6551229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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372
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Brooks BR, Bruccoleri RE, Olafson BD, States DJ, Swaminathan S, Karplus M. CHARMM: A program for macromolecular energy, minimization, and dynamics calculations. J Comput Chem 1983. [DOI: 10.1002/jcc.540040211] [Citation(s) in RCA: 12524] [Impact Index Per Article: 305.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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373
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Swaminathan S, Lower GM, Bryan GT. Nitroreductase-mediated metabolic activation of 2-amino-4-(5-nitro-2-furyl)thiazole and binding to nucleic acids and proteins. Cancer Res 1982; 42:4479-84. [PMID: 6751523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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374
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Swaminathan S, Ichiye T, van Gunsteren W, Karplus M. Time dependence of atomic fluctuations in proteins: analysis of local and collective motions in bovine pancreatic trypsin inhibitor. Biochemistry 1982; 21:5230-41. [PMID: 7171552 DOI: 10.1021/bi00264a019] [Citation(s) in RCA: 138] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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375
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Artman HG, Reppert SM, Perlow MJ, Swaminathan S, Oddie TH, Fisher DA. Characterization of the daily oxytocin rhythm in primate cerebrospinal fluid. J Neurosci 1982; 2:598-603. [PMID: 7077368 PMCID: PMC6564258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The circadian characteristics of the daily rhythm in oxytocin (OT) concentrations in cerebrospinal fluid (CSF) were studied in the rhesus monkey. Monkeys subjected to constant light or constant dark for periods of 3 to 6 days manifested persistence of the CSF OT rhythm. A 12-hr phase shift in the light-dark cycle resulted in a resynchronization of the rhythm to the new lighting schedule within 3 to 4 days. Altering the daily feeding and care schedule during a period of constant darkness did not alter the expression or timing of the CSF OT rhythm significantly. These results suggest that the OT rhythm is endogenously generated and that the daily light-dark cycle normally synchronizes the rhythm to the 24-hr cycle.
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