title: Evaluation of molecularity of rate-limiting step of pore formation by antimicrobial peptides studied using mitochondria as a biosensor.
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.
authors.affiliation: Department of Biotechnology, Caspian Institute of Biological Resources of the Russian Academy of Sciences, ul. Gadjieva 45, Makhachkala 367025, Russia.
authors.forename: Dinara
authors.initials: D
authors.lastname: Aliverdieva
authors.forename: Dmitry
authors.initials: D
authors.lastname: Mamaev
authors.forename: Leona
authors.initials: L
authors.lastname: Snezhkova
authors.forename: Christophor
authors.initials: C
authors.lastname: Sholtz
mesh_terms: D000408:Alamethicin / Q000494:pharmacology*; D000818:Animals; D015374:Biosensing Techniques; D008555:Melitten / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000502:physiology; D010084:Oxidation-Reduction; D010455:Peptides / Q000494:pharmacology*; D051381:Rats; D019802:Succinic Acid / Q000378:metabolism
chemical_list: D010455:Peptides; D008555:Melitten; D000408:Alamethicin; D019802:Succinic Acid