Related Experiment Video
Updated: Jul 27, 2026
14:27
Steady-state, Pre-steady-state, and Single-turnover Kinetic Measurement for DNA Glycosylase Activity
Published on: August 19, 2013
Kinetic studies of dimeric Ncd: evidence that Ncd is not processive
1Department of Biological Sciences, 518 Langley Hall, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Biochemistry
|February 26, 2000
Summary
Ncd, a motor protein, moves to microtubule minus-ends. Its ATP hydrolysis rate is 23 s(-1), but ADP release is the slowest step, limiting turnover and indicating non-processive ATP hydrolysis.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Ncd is a kinesin-related motor protein responsible for minus-end directed movement along microtubules.
- Understanding the kinetic mechanisms of motor proteins is crucial for elucidating cellular transport processes.
Purpose of the Study:
- To investigate the kinetics of Ncd motor protein using a dimeric construct (MC1).
- To define the minimal kinetic mechanism of Ncd's interaction with microtubules and ATP.
Main Methods:
- Utilized acid chemical quench flow and stopped-flow kinetic methods.
- Measured ATP hydrolysis, mantATP binding, mantADP release, and MC1-microtubule binding/dissociation rates.
Main Results:
- Defined a minimal kinetic mechanism for Ncd, with ATP hydrolysis at 23 s(-1) preceding dissociation at 13 s(-1).
- MantADP release (3.7 s(-1)) was identified as the slowest step, limiting steady-state turnover.
- Ncd demonstrated non-processive ATP hydrolysis, unlike kinesin, based on stoichiometric burst amplitude.
Conclusions:
- The ATP-promoted detachment pathway of Ncd from microtubules shares similarities with kinesin.
- Key differences include the rate-limiting ADP release and non-processive nature of Ncd's ATP hydrolysis.
- These findings provide critical insights into the distinct functional mechanisms of microtubule motor proteins.
