Implications of diffusion-controlled limit for processivity of dimeric kinesin head domains.
The diffusion-limited rate for association of the ADP complex of dimeric DKH392 kinesin head domains with a microtubule was estimated to be 2-3 x 10(7) M-1 s-1 based on approximation of a microtubule as a highly elongated prolate ellipsoidal adsorber of 100% efficiency. This theoretical bimolecular rate is approximately 100-fold smaller than the experimental rate, kcat/KMT0.5, for DKH392 that was determined from the stimulation of the steady-state ATPase rate by microtubules. The large difference between these two estimates of the bimolecular rate indicates that it is likely that dimeric DKH392 hydrolyzes multiple ATP molecules during each diffusional encounter with a microtubule.
Hackney
D D
DD
Department of Biological Science, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D004058:Diffusion; D004330:Drosophila; D006868:Hydrolysis; D066298:In Vitro Techniques; D016547:Kinesins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D007700:Kinetics; D008870:Microtubules / Q000502:physiology; D008954:Models, Biological; D015394:Molecular Structure; D009068:Movement / Q000502:physiology; D011487:Protein Conformation
D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D016547:Kinesins