Related Experiment Video
Updated: May 22, 2026
Multi-parameter Measurement of the Permeability Transition Pore Opening in Isolated Mouse Heart Mitochondria
Published on: September 7, 2012
Evaluation of molecularity of rate-limiting step of pore formation by antimicrobial peptides studied using
Dinara Aliverdieva1, Dmitry Mamaev, Leona Snezhkova
1Department of Biotechnology, Caspian Institute of Biological Resources of the Russian Academy of Sciences, ul. Gadjieva 45, Makhachkala 367025, Russia.
Abstract:
Toxic agents, derived from bee or hornet venoms and from fungi - melittin, mastoparan, and alamethicin are able to permeabilize biological membranes. We studied the initial steps of pore formation by these peptides in rat liver mitochondria preparations (RLM) generating transmembrane potential (ΔΨ). RLM has been used as a potassium transmembrane current (PTC) sensor. The PTC induced in RLM depends linearly on the degree of steady-state activation of RLM respiration. The concentration order of such activation by melittin in a "potassium" incubation medium containing 6mM Mg(2+) was 2.01±0.15. In the case of mastoparan, the reaction order was 1.83±0.23. The first steady-state phase of activation of RLM respiration by alamethicin was not detected in "Tris" incubation medium; it appeared only after addition of KCl. The order of the reaction limiting such activation was 1.92±0.07. It is suggested that PTC in this phase is determined by the channels with the lowest degree of oligomerization formed by "dimers". The ratio of equally active membrane concentrations of peptides obviously reflects the ratio of average lifetimes (ALT) for corresponding "dimers" (alamethicin and melittin, 38.5; mastoparan and melittin, 0.32). It is concluded that the results of this investigation may be useful for comparative testing of perspective pharmaceuticals.
Insights
Toxic peptides like melittin permeabilize membranes by forming pores. This study quantizes pore formation in rat liver mitochondria, revealing insights into peptide-membrane interactions for pharmaceutical development.
Area of Science:
- Biochemistry
- Biophysics
- Pharmacology
Background:
- Melittin, mastoparan, and alamethicin are toxic peptides known to permeabilize biological membranes.
- Understanding the initial steps of peptide-induced pore formation is crucial for various applications, including drug development.
Purpose of the Study:
- To investigate the initial pore formation mechanisms of melittin, mastoparan, and alamethicin in rat liver mitochondria (RLM).
- To quantify the relationship between peptide concentration and membrane permeabilization using RLM as a sensor.
Main Methods:
- Utilized rat liver mitochondria (RLM) preparations as a sensor for transmembrane potential (ΔΨ) and potassium transmembrane current (PTC).
- Measured the steady-state activation of RLM respiration induced by varying concentrations of melittin, mastoparan, and alamethicin under different incubation conditions.
- Determined the reaction order for peptide-induced activation and calculated the ratio of average lifetimes (ALT) for peptide dimers.
Main Results:
- The induced PTC in RLM showed a linear dependence on the steady-state activation of RLM respiration.
- The concentration orders for activation by melittin and mastoparan were determined as 2.01±0.15 and 1.83±0.23, respectively.
- Alamethicin-induced activation was observed only after KCl addition, with a reaction order of 1.92±0.07, suggesting dimer-mediated pore formation.
Conclusions:
- The study suggests that the initial phase of PTC is mediated by peptide dimers.
- The ratio of equally active membrane concentrations reflects the average lifetimes of these dimers.
- Findings may aid in the comparative testing of novel pharmaceutical agents targeting membrane permeability.
