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121.
COMPARATIVE PHOTOCHEMICAL ANALYSIS OF HIGHLY PURIFIED 124 KILODALTON OAT and RYE PHYTOCHROMES in vitro 总被引:3,自引:0,他引:3
J. Clark Lagarias John M. Kelly Karen L. Cyr William O. Smith Jr 《Photochemistry and photobiology》1987,46(1):5-13
Abstract A direct comparison of the photochemical interconversions between red (Pr -) and far-red (Pfr -) absorbing forms of highly-purified 124 kDa oat and rye phytochromes under identical experimental conditions was performed. In two different buffer systems at 5°C, the quantum yields for the Pr to Ptr and Pfr to Pr phototransformations under constant red and far-red illumination, φ r and φfr respectively, were determined to be 0.152-0.154 and 0.060-0.065 for oat preparations and 0.172-0.174 and 0.074-0.078 for rye preparations. These values as well as the wavelength dependence of the photoequilibrium produced under continuous illumination throughout the visible and near-ultraviolet spectrum were based on the absorption spectra of the two phytochrome preparations and revised molar absorption coefficients. The molar absorption coefficients were estimated by quantitative amino acid analysis and shown to be identical for the two monocot phytochromes (i.e. 132 mM −1 cm−1 at the red absorption maximum for the Pr form). Because these measurements were performed under identical experimental conditions, including buffer, temperature, light fluence rate, and instrumentation, the differences observed must reflect structural features inherent to the two different monocotyledonous phytochromes. 相似文献
122.
Robin D. Clark 《Journal of heterocyclic chemistry》1983,20(5):1393-1395
N-substituted 4-(2-morpholinyl)indoles were prepared from 1-(t-butoxycarbonyl)-4-acetylindole (7) which was itself prepared from 4-cyanoindole. Bromination of ketone 7, followed by reaction with amines and subsequent sodium borohydride reduction, gave amino alcohols. These were converted to α-chloro amides that were cyclized to lactams. Lithium aluminum hydride reduction served both to remove the t-BOC protecting group and to reduce the lactams to the 4-(2-morpholinyl) indoles. 相似文献
123.
C R Clark C L McMillian J F Hoke K D Campagna W R Ravis 《Journal of chromatographic science》1987,25(6):247-251
An improved liquid chromatographic procedure is described for the quantitative determination of sulindac, sulindac sulfone, and sulindac sulfide from serum. The procedure makes use of acetonitrile extraction of the compounds of interest from acidified serum samples. Under these conditions extraction efficiencies in the 85 percent range are obtained for each of the compounds. The liquid chromatographic separation of the compounds of interest and the internal standard (indomethacin) is accomplished in an isocratic elution procedure using a nitrile (CN) stationary phase. The HPLC separation procedure is completed in less than 10 minutes, giving excellent resolution and peak shape. 相似文献
124.
P. A. Clark 《Theoretical chemistry accounts》1972,28(1):75-80
CNDO/2 calculations of the electronic properties of the series of isomeric butenes and pentenes yield ionization potentials which reproduce the observed trends. These are interpreted in terms of the charge distribution effects of the alkyl groups.
Presented in part at the Eighth Theoretical Chemistry Symposium held at the Batelle Institute, Geneva, Switzerland; March 26–30, 1972. 相似文献
Zusammenfassung CNDO/2 Rechnungen für die Butan- und Penten-Isomeren ergeben die richtigen Trends für die Ionisierungspotentiale. Sie werden im Zusammenhang mit der Änderung der Ladungsverteilung infolge Methylsubstitution diskutiert.
Résumé Des calculs CNDO/2 des propriétés électroniques des séries d'isomères du butène et du pentène fournissent des potentiels d'ionisation qui reproduisent les tendances observées. Les distributions de charge calculées pour les molécules sont utilisées pour interpréter les propriétés observées en termes d'effet du substituant alkyle.
Presented in part at the Eighth Theoretical Chemistry Symposium held at the Batelle Institute, Geneva, Switzerland; March 26–30, 1972. 相似文献
125.
The natural atomic orbital/point (NAO-PC) model originally developed to calculate molecular electrostatic potentials (MEPs) and multiple moments based on the AM1 wave function has been extended to PM3. As for AM1, NAO-PC/PM3 reproduces dipole moments calculated by the standard PM3 method very well. There is also a surprisingly good correlation between experimental and calculated quadrupole moments. The MEPs calculated using PM3/NAO-PC are found to be in better agreement with those given by RHF/6-31G* than those obtained from the PM3 wave function using Coulson charges. On the other hand, the NAO-PC model is often slightly worse then the method implemented in MOPAC-ESP. The MEPs calculated using our model based on the PM3 wave function are often in better agreement with those given by RHF/6-31G* than those obtain with AM1. © 1994 by John Wiley & Sons, Inc. 相似文献
126.
R. M. Lindstrom R. Zeisler D. H. Vincent R. R. Greenberg C. A. Stone E. A. Mackey D. L. Anderson D. D. Clark 《Journal of Radioanalytical and Nuclear Chemistry》1993,167(1):121-126
An instrument for neutron capture prompt gamma-ray activation analysis (PGAA) has been constructed as part of the Cold Neutron Research Facility at the 20 MW National Institute of Standards and Technology Research Reactor. The neutron fluence rate (thermal equivalent) is 1.5·108 n ·cm–2·s–1, with negligible fast neutrons and gamma-rays. With compact geometry and hydrogen-free construction, the sensitivity is sevenfold better than an existing thermal instrument. Hydrogen background is thirtyfold lower. 相似文献
127.
Phase memory decays were obtained from the transient signals sampled within 50 ns of laser excitation by time resolved electron spin echo (ese) spectroscopy in normal protonated, deuterated, deuterated 15N photosynthetic algae and broken chloroplasts. Previously, it has been shown that application of time resolved ese to study these systems, in particular, gives rise to two kinds of signals (standard and special ese). The standard ese signal at g = 2.0023 and the special ese signal exhibit similar electron spin echo envelope modulation (eseem). The modulation frequency and pattern can be identified with that obtained from stable oxidized P700 in the same system. The two lower field resonances of the standard ese signal do not show eseem. The results support the proposed mechanism for formation of special ese and the notion that the standard ese is due to at least two radicals. It is also demonstrated that we can observe eseem of P+700 under ambient temperature conditions. 相似文献
128.
Clark TD Ferrigno R Tien J Paul KE Whitesides GM 《Journal of the American Chemical Society》2002,124(19):5419-5426
This article presents a strategy for the fabrication of ordered microstructures using concepts of design inspired by molecular self-assembly and template-directed synthesis. The self-assembling components are 4-microm-thick hexagonal metal plates having sides 10 microm in length ("hexagons"), and each template consists of a 4-microm-thick circular metal plate surrounding a central cavity, the perimeter of which is complementary in shape to the external edges of a two-dimensional, close-packed array of hexagons. The hexagons and templates (collectively, "pieces") were fabricated via standard procedures and patterned into hydrophobic and hydrophilic regions using self-assembled monolayers (SAMs). Templated self-assembly occurs in water through capillary interactions between thin films of a nonpolar liquid adhesive coating the hydrophobic faces of the pieces. The hexagons tile the cavities enclosed by the templates, and the boundaries of the cavities determine the sizes and shapes of the assemblies. Curing the adhesive with ultraviolet light furnishes mechanically stable arrays having well-defined morphologies. By allowing control over the structures of the resulting aggregates, this work represents a step toward the development of practical methods for microfabrication based on self-assembly. 相似文献
129.
James B. Clark Arthur L. Smirl Eric W. Van Stryland H.J. Mackey B.R. Russell 《Chemical physics letters》1981,78(3):456-460
The population kinetics and the rotational diffusion of the rhodamine B monomer and dimer were measured by using picosecond pulses from a mode-locked Nd : YAG laser to induce and time resolve the concentration-dependent transient absorption saturation of various aqueous solutions of this organic dye. 相似文献
130.