Membrane damage: common mechanisms of induction and prevention

Abstract

SUMMARYCommon features in the induction of pores by various agents are as follows: induction is stochastic and progressive; damage by different agents is often synergistic and limited. The prevention of membrane damage is affected by trivalent and divalent cations, by low pH, by low ionic strength and by high osmotic pressure. The inhibitory role of protons and divalent cations is considered in greater detail: pore-forming agents can be classified into two groups: channels across planar lipid bilayers induced by the first group display voltage-sensitive, reversible inhibition by divalent cations; channels of the second group show voltage-insensitive, irreversible inhibition by divalent cations. A search for the ligands to which divalent cations and protons bind has proved elusive. Comparison with the phenomenon of

Structural and functional characterisation of two proteolytic fragments of the bacterial protein toxin, pneumolysin

“…That the C-terminal fragment, with its domain structure still largely complete, can bind and self-associate strongly indicates that it fulfils these two functions in complete pneumolysin. This compares favourably with previous data obtained by us indicating that C-terminal deletions from pneumolysin [20] and antibodies whose epitopes lie in the C-terminal region [21] inhibit its binding activity while mutation of particular residues within the sequence of K2 away from the C-terminus inhibit pore-formation [22]. Similar mutational results have been obtained in streptolysin O (another thiol-activated toxin) by Palmer and co-workers [23,24], and in perfringolysin O the C-terminal fragment generated using subtilisin Carlsberg also has similar structural and functional attributes [19].…”

Membrane perturbing properties of natural phenolic and resorcinolic lipids

“…The lysis of cells induced by various compounds can be modulated by the presence of divalent cations the medium. This protective effect been demonstrated for many different lytic agents [17,[23][24][25]. I found that the lysis of erythrocytes induced by investigated lipids from CNSL was also inhibited in the presence of divalent cations ( Fig.…”

Zinc in wound healing: Theoretical, experimental, and clinical aspects

“…4,5 In addition to its role in nucleic acid and protein synthesis, carbohy-drate metabolism, and oxygen transport, zinc is now known to be instrumental in stabilizing cellular membranes. 6,7 Zinc-finger proteins are a family of more than 2,000 transcription factors that bind specifically to DNA and activate transcription of growth factors, 4,8-10 cytoprotective proteins, 11 and are regulators of adult hematopoietic stem cells. 12 Apart from its importance in protein complexes, the zinc ion is closely involved in intracellular signaling and neurotransmission.…”