Rheological properties of liver actin solutions |
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Authors: | W. Oppermann B. Jaberg |
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Affiliation: | (1) Institut für Physikalische Chemie, Technischen Universität Clausthal, Adolf-Römer-Straße 2a, D-3392 Clausthal-Zellerfeld, BRD;(2) Institut für Pharmakologie und Toxikologie, Universität Giessen, Frankfurter Straße 107, D-6300 Giessen, BRD |
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Abstract: | G-actin prepared from pork liver and purified to give a product of 95–98% purity was polymerized to F-actin in a rotational dynamic viscometer. The rheological properties were investigated during the course of polymerisation and after polymerisation.G andG measured at frequencies around 0.1 Hz increased strongly during the first 3 hours of the reaction and then slowly approached a constant value in the range of 10–50 mPa. The rise during polymerisation was more than two orders of magnitude. When a solution of F-actin was subjected to steady shear at a high shear rate for a short period of time and subsequently dynamic measurements were performed, then a considerably smallerG (about 70% smaller) was observed immediately after cessation of the steady shear.G then increased with time and approached its initial value.When measuring the viscosity of F-actin solutions as a function of shear rate, a strong shear thinning effect was seen which did not vanish even at shear rates as low as 0.001 s–1. Even at this low shear rates, a pronounced yield maximum was observed before reaching the steady state. Oscillatory experiments showed a remarkably weak frequency dependence ofG.The results imply that F-actin solutions are largely structured forming a weak temporary network which can be easily destroyed by application of high shear rates. It seems most likely that the destruction occurs by a reversible, shear induced depolymerisation process. |
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Keywords: | Liver actin polymerisation viscoelastic properties of liver actin shear thinning temporary network shear-induced degradation |
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