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G Holzwarth

Publications and source records attributed to G Holzwarth.

25 records · Page 2Linked to original sources
PubMed1971

Optical activity of membrane suspensions: calculation of artifacts by Mie scattering theory.

The circular dichroism, optical rotatory dispersion, and optical density of a suspension of erythrocyte ghosts are calculated from the measured optical properties of solubilized ghosts by classical general scattering theory (Mie theory). The ghost is represented by a solvent-filled spherical shell 7 nm (70 A) thick and 3.5 mum in radius. The 3- to 5-nm red shifts and unusual band shapes observed in the circular dichroism and optical rotary dispersion of suspensions of the intact ghosts, but not in the solubilized membranes, are reproduced by these calculations. Both differential absorption and differential scattering of left-and right-circularly polarized light contribute significantly to the calculated circular dichroism spectra. The artifacts of small membrane vesicles are shown to be less than those of intact ghosts. It is concluded that the characteristic anomalies in the optical activity of membrane suspensions are artifactual.

Cell Membrane↗
PubMedDate not supplied

Mobility surfaces for field-inversion gel electrophoresis of linear DNA.

The mobility of linear DNA during field-inversion gel electrophoresis was measured as a function of molecular weight Mr, pulse time t, and field strength E. Values of Mr between 48.5 and 194 kilobase pairs (kb), E from 5 to 14 V/cm and pulse times of 0.3 to 12 s were used. The data are presented as three-dimensional surfaces of mobility: E:t for fixed Mr or graphs of mobility: Mr:t for fixed E. The surfaces are not smoothly increasing functions of E, Mr, or t but instead show a valley with minimum mobility and a steep rise in mobility as t increases. For a field of 10 V/cm, 1% agarose gels, and 3:1 ratio of forward:back pulse time, the forward switching time t* at which the mobility changes most rapidly is given by t* = (0.034 +/- 0.003) Mr for Mr in kb and t* in seconds. The data and equations delineate the best conditions to achieve a particular separation.

Bacteriophages↗