No abstract

Kinesins are motor proteins which convert the chemical energy of ATP into mechanical energy to move along proteinaceous microtubule rails and to transport different cargoes to defined intracellular destinations. It is well documented that following the track of a single protofilament is the thermodynamically most effective mechanism of kinesin movement along microtubules. However, the question arises what happens when a kinesin molecule encounters a hindrance along the protofilament. The present study describes a simple, cell-free approach which enables to study the effects of structural blockages on kinesin-based transport. This experimental approach uses dimeric conventional kinesin moving nanometre-sized gold beads along immobilized microtubules whose surface has been irreversibly decorated by blocking proteins. We demonstrated that the continuous bead transport temporarily stopped at sites of blockages, but usually continued after a certain resting time. Our results suggest that single dimeric kinesin molecules are able to change to another protofilament if the next tubulin dimer where the second head should bind is blocked. A bypassing mechanism is discussed which is considered to be one fundamental prerequisite to realize a kinesinmediated cargo-transport along microtubules over long distances, required for e.g., the fast axonal transport in motor neurons.

No abstract

Neben dem Klimawandel gilt die Luftverschmutzung als eines der wichtigsten Umweltthemen der heutigen Zeit. Dabei sind die Quellen sowohl anthropogenen als auch natürlichen Ursprungs zu suchen. Die Überwachung der Freisetzung von umwelt‐ und gesundheitsschädlichen Schadstoffen bedarf daher besonderer Aufmerksamkeit. Mit einem mobilen Messsystem für Aerolole und Partikel lässt sich die Luftqualität flexibel überwachen.

Nur mit Online‐ oder Inline‐Analysentechnik können kritische Parameter bei kontinuierlichen Prozessen zuverlässig und engmaschig überwacht werden.