TY - JOUR
T1 - Microtubule Disassembly
T2 - A Quantitative Kinetic Approach for Defining Endwise Linear Depolymerization
AU - Purich, Daniel L.
AU - Karr, Timothy L.
AU - Kristofferson, David
N1 - Funding Information:
This work was supported by National Institute of Health grant NS 12418.
PY - 1982/1/1
Y1 - 1982/1/1
N2 - This chapter presents the pertinent theoretical aspects and describes the experimental approaches to characterize the mechanism of depolymerization. To analyze endwise depolymerization quantitatively, various premises must hold: (1) the polymer undergoes stepwise disassembly in a series first-order fashion, (2) the off-rate constant is independent of polymer length over the course of depolymerization, (3) the on-rate constant is zero, (4) turbidity is a measure of the remaining polymer weight concentration and is independent of the polymer length distribution, and (5) the concentrations of the various polymer lengths may be estimated by use of electron microscopy. Primarily, the chapter examines the kinetics of the series first-order decay of polymer and its expression in terms of remaining polymer weight concentration. For indefinite polymerization processes that result from entropydriven condensation equilibria, there are three ways to effect depolymerization: (1) dilution to below the critical concentration, (2) reduction of the temperature to destabilize the polymer, and (3) addition of a reagent to reduce the concentration of the form of the protomer in equilibrium with the polymer. The methods for bringing about such changes must be rapid relative to the time course of depolymerization; otherwise, the kinetics of effecting the depolymerization process will obscure the kinetics of polymer loss.
AB - This chapter presents the pertinent theoretical aspects and describes the experimental approaches to characterize the mechanism of depolymerization. To analyze endwise depolymerization quantitatively, various premises must hold: (1) the polymer undergoes stepwise disassembly in a series first-order fashion, (2) the off-rate constant is independent of polymer length over the course of depolymerization, (3) the on-rate constant is zero, (4) turbidity is a measure of the remaining polymer weight concentration and is independent of the polymer length distribution, and (5) the concentrations of the various polymer lengths may be estimated by use of electron microscopy. Primarily, the chapter examines the kinetics of the series first-order decay of polymer and its expression in terms of remaining polymer weight concentration. For indefinite polymerization processes that result from entropydriven condensation equilibria, there are three ways to effect depolymerization: (1) dilution to below the critical concentration, (2) reduction of the temperature to destabilize the polymer, and (3) addition of a reagent to reduce the concentration of the form of the protomer in equilibrium with the polymer. The methods for bringing about such changes must be rapid relative to the time course of depolymerization; otherwise, the kinetics of effecting the depolymerization process will obscure the kinetics of polymer loss.
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U2 - 10.1016/0076-6879(82)85044-1
DO - 10.1016/0076-6879(82)85044-1
M3 - Article
C2 - 7121281
AN - SCOPUS:0020009438
SN - 0076-6879
VL - 85
SP - 439
EP - 450
JO - Methods in Enzymology
JF - Methods in Enzymology
IS - C
ER -