A magnetic viscometer for shear-sensitive macromolecules.
This paper is a report about a rotation-viscometer with a submerged rotor which has been developed for measuring the viscosity of biological macromolecules. The device avoids the effects of surface disturbance. The rotor is centered and height-balanced electromagnetically and is controlled by a light barrier. The driving force is a rotating electromagnetic field and rotor revolution periods are measured by an electronic timer controlled by a second ligh barrier. Shearing effects are negligible if very slow revolutions are pre-selected; thus, intrinsic viscosity values for DNA can be obtained by merely extrapolating the concentration dependence. In contrast to DNA, chromatin has a very low viscosity with almost no dependence on concentration. If the ionic strength of a chromatin solution is decreased, the viscosity increases due to structural unfolding.
D000818:Animals; D002417:Cattle; D002843:Chromatin; D004247:DNA; D055590:Electromagnetic Phenomena / Q000295:instrumentation*; D046911:Macromolecular Substances; D008968:Molecular Conformation; D009994:Osmolar Concentration; D014783:Viscosity
D002843:Chromatin; D046911:Macromolecular Substances; D004247:DNA