RESUMO
Rotational spectra have been assigned for five isotopic species of the OC...HBr hydrogen-bonded molecular complex by using pulsed microwave Fourier transform spectroscopy in a Fabry-Perot cavity and a pulsed supersonic nozzle as the molecular source. The rotational constants, centrifugal distortion constants, Br nuclear-quadrupole-coupling constants, and Br spin-rotation constants were determined and from them, the vibrationally averaged structure of OCHBr was derived. This structure is consistent with a linear geometry at equilibrium and an atomic arrangement as written above. The intermolecular potential binding CO to HBr is discussed.
RESUMO
Quasi-elastic or dynamic light scattering has been used to examine the translational diffusion properties of the enzyme pyruvate oxidase (pyruvate: ferricytochrome beta 1 oxidoreductase, EC 1.2.2.2.). Controlled proteolysis of the enzyme converts the native form of the enzyme to a protease-activated form which has a specific activity about 20-fold greater than the native oxidase. Light scattering studies indicate no significant change in the size or shape of pyruvate oxidase as a result of this proteolytic activation. In both cases the enzyme may be characterized as a hydrated sphere with a Stokes radius of about 53A. The sedimentation velocity-diffusion technique was used to obtain the molecular weight of this tetrameric enzyme, about 252 000 with a value of f/f0 of 1.25.
Assuntos
Piruvato Oxidase , Centrifugação com Gradiente de Concentração , Ativação Enzimática , Escherichia coli/enzimologia , Conformação Molecular , Peso Molecular , Piruvato Oxidase/metabolismo , Espectrofotometria , Tripsina/farmacologiaRESUMO
The wild-type New Jersey serotype of vesicular stomatitis virus generated two types of defective interfering T-particles. The physical properties of these particles and the wild-type virion were determined by laser light scattering spectroscopy, sedimentation measurements, and electron microscopy.
Assuntos
Vírus Defeituosos/análise , Vesiculovirus/análise , Vírus Defeituosos/ultraestrutura , Lasers , Peso Molecular , Espalhamento de Radiação , Vesiculovirus/ultraestruturaRESUMO
Laser light-scattering spectroscopy has been used to determine the diffusion coefficients of vesicular stomatitis virus and three of its defective particles in order to calculate their molecular weights.
Assuntos
Vírus Defeituosos/análise , Vírus da Estomatite Vesicular Indiana/análise , Animais , Linhagem Celular , Centrifugação com Gradiente de Concentração , Cricetinae , Vírus Defeituosos/isolamento & purificação , Rim , Lasers , Métodos , Peso Molecular , Espalhamento de Radiação , Análise Espectral , Vírus da Estomatite Vesicular Indiana/isolamento & purificação , Cultura de VírusRESUMO
Optical heterodyne spectra of laser light quasi-elastically scattered by falling water droplets (1-10-micro radius) in a diffusion cloud chamber were used to determine the droplet size distribution. The rate of fall depends on radius in a known way, thus yielding a heterodyne spectrum manifesting a distribution of Doppler shifts. This spectrum, in conjunction with the calculated Mie scattering intensity as a function of droplet radius, provides a direct measure of the droplet size distribution for droplets large enough that Brownian motion is negligible. The experiments described in this paper demonstrate the technique and establish the potential for further more quantitative studies of size distributions.