Communication: Activation energy of tension-induced pore formation in lipid membranes.
Tension plays a vital role in pore formation in biomembranes, but the mechanism of pore formation remains unclear. We investigated the temperature dependence of the rate constant of constant tension (σ)-induced pore formation in giant unilamellar vesicles of lipid membranes using an experimental method we developed. By analyzing this result, we determined the activation energy (Ua) of tension-induced pore formation as a function of tension. A constant (U0) that does not depend on tension was found to contribute significantly to Ua. Analysis of the activation energy clearly indicated that the dependence of Ua on σ in the classical theory is correct, but that the classical theory of pore formation is not entirely correct due to the presence of U0. We can reasonably consider that U0 is a nucleation free energy to form a hydrophilic pre-pore from a hydrophobic pre-pore or a region with lower lateral lipid density. After obtaining U0, the evolution of a pre-pore follows a classical theory. Our data provide valuable information that help explain the mechanism of tension-induced pore formation in biomembranes and lipid membranes.
Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan.
Mohammad Abu Sayem
MA
Karal
Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan.
Masahito
M
Yamazaki
D000818:Animals; D002417:Cattle; D010713:Phosphatidylcholines / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D013500:Surface Tension; D013816:Thermodynamics
D010713:Phosphatidylcholines; D012710:Serum Albumin, Bovine; C017251:1,2-oleoylphosphatidylcholine