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CPP: Chemische Physik und Polymerphysik

CPP 21: POSTER B

CPP 21.4: Poster

Tuesday, March 25, 2003, 19:00–21:00, ZEU/250

Modeling oscillatory Microtubule-Polymerization — •Martin Hammele and Walter Zimmermanna — Theor. Physik, Universität des Saarlandes, 66041 Saarbrücken

Polymerization of microtubules is ubiquitous in biological cells and under certain conditions it becomes oscillatory in time. Here simple reaction models are analyzed that capture such oscillations as well as the length distribution of microtubules. We assume reaction conditions that are stationary over many oscillation periods, and it is a Hopf bifurcation that leads to a persistent oscillatory microtubule polymerization in these models. Both, a catastrophe rate that depends on the density of guanosine triphosphate (GTP) liganded tubulin dimers and a delay reaction, such as the depolymerization of shrinking microtubules or the decay of oligomers, support homogeneous oscillations. Close to threshold a so–called amplitude equation is derived and it is shown that the bifurcation to microtubule oscillations is supercritical. Moreover for a large parameter range spatially homogeneous oscillations turn out to be unstable and are replaced by spatio-temporal chaotic polymerization behavior (Benjamin-Feir resonance).