Geminate Recombination
Mostrando 1-12 de 13 artigos, teses e dissertações.
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1. Condutividade induzida por radiação ionizante no Mylar (PET) e Kapton (polimiidia). / Radiation-induced conductivity in Mylar (PET) and Kapton (polymide)
In this work we present extensive results of measurements of the prompt and delayed radiation-induced conductivity of samples of PET and Kapton. Experimental parameters, such as the effective energy of the radiation, the exposure rate, the total dose, the value of the applied electric field, the nature of the electrodes, and the ambienta1 conditions were cha
Publicado em: 1986
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2. Geminate recombination of O2 and hemoglobin.
The photolysis of HbO2 and HbCO has been studied by measuring transient absorption spectra in the Soret region after excitation with picosecond pulses at 530 nm. Dissociation occurred promptly in both cases, followed (for HbO2) by geminate recombination of ca. 40% of the photodissociated O2 with a lifetime of 200 +/- 70 psec (25 degrees C). No recombination
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3. Hemerythrin's oxygen-binding reaction studied by laser photolysis.
The dioxygen--iron bond in oxyhemerythrin is shown to be photosensitive. The recombination reaction after photodissociation depends strongly on solvent viscosity. In water (eta = 1 centipoise or 1 x 10(-3) Pa . s) the recombination is monophasic and second-order in solvent oxygen concentration, with a bimolecular rate coefficient of 2.9 x 10(7) M-1 s-1. In a
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4. Temperature-derivative spectroscopy: a tool for protein dynamics.
A relaxation method that measures the derivative of a population with respect to temperature is introduced and used to study the recombination of CO to sperm whale myoglobin after a photolyzing flash. Measurement of the geminate process in the infrared CO-stretch bands shows distributed activation enthalpies with different distributions for each band, transi
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5. Oxygen and CO binding to triply NO and asymmetric NO/CO hemoglobin hybrids.
The bimolecular and geminate CO recombination kinetics have been measured for hemoglobin (Hb) with over 90% of the ligand binding sites occupied by NO. Since Hb(NO)4 with inositol hexaphosphate (IHP) at pH below 7 is thought to take on the low affinity (deoxy) conformation, the goal of the experiments was to determine whether the species IHPHb-(NO)3(CO) also
The Biophysical Society.
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6. Nonexponential relaxation after ligand dissociation from myoglobin: a molecular dynamics simulation.
Molecular dynamics simulations of myoglobin after ligand photodissociation show that the out-of-plane motion of the heme iron has a rapid subpicosecond phase followed by a slower nonexponential process involving more global protein relaxation. Individual trajectories show rather different behavior, suggesting there is an inhomogeneous component to the relaxa
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7. Molecular dynamics simulations of cooling in laser-excited heme proteins.
In transient optical experiments the absorbed photon raises the vibrational temperature of the chromophore. In heme proteins at room temperature conversion of a 530-nm photon into vibrational energy is estimated to raise the temperature of the heme by 500-700 K. Cooling of the heme is expected to occur mainly by interacting with the surrounding protein. We r
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8. Unveiling functional protein motions with picosecond x-ray crystallography and molecular dynamics simulations
A joint analysis of all-atom molecular dynamics (MD) calculations and picosecond time-resolved x-ray structures was performed to gain single-molecule insights into mechanisms of protein function. Ensemble-averaged MD simulations of the L29F mutant of myoglobin after ligand dissociation reproduce the direction, amplitude, and time scales of crystallographical
National Academy of Sciences.
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9. Nanosecond time-resolved absorption studies of human oxyhemoglobin photolysis intermediates.
The time-resolved spectra of photoproducts from ligand photodissociation of oxyhemoglobin are measured in the Soret spectral region for times from 10 ns to 320 microseconds after laser photolysis. Four processes are detected at a heme concentration of 80 microM: a 38-ns geminate recombination, a 137-ns tertiary relaxation, and two bimolecular processes for r
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10. Infectious mutants of cassava latent virus generated in vivo from intact recombinant DNA clones containing single copies of the genome.
Intact recombinant DNAs containing single copies of either component of the cassava latent virus genome can elicit infection when mechanically inoculated to host plants in the presence of the appropriate second component. Characterisation of infectious mutant progeny viruses, by analysis of virus-specific supercoiled DNA intermediates, indicates that most if
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11. Nanosecond absorption spectroscopy of hemoglobin: elementary processes in kinetic cooperativity.
A nanosecond absorption spectrometer has been used to measure the optical spectra of hemoglobin between 3 ns and 100 ms after photolysis of the CO complex. The data from a single experiment comprise a surface, defined by the time-ordered set of 50-100 spectra. Singular value decomposition is used to represent the observed spectra in terms of a minimal set of
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12. Different dissociation pathways and observation of an excited deoxy state in picosecond photolysis of oxy- and carboxymyoglobin.
Picosecond transient absorption spectra of Mb, MbCO, and MbO2 have been studied at time delays of up to 10 ns after excitation at 353 nm. Particular attention has been paid to the rapid spectral changes that occur in the Soret region during the first 50 ps in MbCO and MbO2. In MbCO both the bleaching of the Soret peak (feature I) and the appearance of new de