Biomaterial Database

The interaction of phthalocyanine with planar lipid bilayers. Photodynamic inactivation of gramicidin channels. 1993

T I Rokitskaya, and Y N Antonenko, and E A Kotova

A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russian Federation.

The effect of phthalocyanines, the potent photodynamic sensitizers, on the electric properties of the bilayer lipid membrane (BLM) is studied. It is shown, that tetrasulfonated, as well as trisulfonated, aluminium phthalocyanine do not alter the conductance of BLM, but elicit certain changes in the boundary potential difference, which points in favor of dye adsorption on BLM. Under the conditions of intense visible light irradiation, the phthalocyanines cause an increase in the conductance, resulting in the irreversible breakdown of BLM, formed from soy bean phosphatidylcholine, but fail to change the conductance of BLM, formed from diphytanoilphosphatidylcholine. The phthalocyanine-sensitized inactivation of gramicidin channels incorporated into BLM is observed under the conditions of weak visible light irradiation using an He-Ne laser. The photodynamic blockage of model ionic channels is considerably suppressed after oxygen depletion. The phenomenon consists of a marked reduction of a number of open channels, probably due to photomodification of tryptophan residues, essential for gramicidin functioning. The mechanism of the channel inactivation, involving the photosensitized reaction of the II type, and the relevance to the interaction of sensitizers with biomembranes, is discussed.

UI	MeSH Term	Description	Entries
D007211	Indoles	Benzopyrroles with the nitrogen at the number one carbon adjacent to the benzyl portion, in contrast to ISOINDOLES which have the nitrogen away from the six-membered ring.
D007473	Ion Channels	Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.	Membrane Channels,Ion Channel,Ionic Channel,Ionic Channels,Membrane Channel,Channel, Ion,Channel, Ionic,Channel, Membrane,Channels, Ion,Channels, Ionic,Channels, Membrane
D008027	Light	That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.	Light, Visible,Photoradiation,Radiation, Visible,Visible Radiation,Photoradiations,Radiations, Visible,Visible Light,Visible Radiations
D008051	Lipid Bilayers	Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.	Bilayers, Lipid,Bilayer, Lipid,Lipid Bilayer
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D006096	Gramicidin	A group of peptide antibiotics from BACILLUS brevis. Gramicidin C or S is a cyclic, ten-amino acid polypeptide and gramicidins A, B, D are linear. Gramicidin is one of the two principal components of TYROTHRICIN.	Gramicidin A,Gramicidin A(1),Gramicidin B,Gramicidin C,Gramicidin D,Gramicidin Dubos,Gramicidin J,Gramicidin K,Gramicidin NF,Gramicidin P,Gramicidin S,Gramicidins,Gramoderm,Linear Gramicidin,Gramicidin, Linear
D017319	Photosensitizing Agents	Drugs that are pharmacologically inactive but when exposed to ultraviolet radiation or sunlight are converted to their active metabolite to produce a beneficial reaction affecting the diseased tissue. These compounds can be administered topically or systemically and have been used therapeutically to treat psoriasis and various types of neoplasms.	Photosensitizer,Photosensitizers,Photosensitizing Agent,Photosensitizing Effect,Photosensitizing Effects,Agent, Photosensitizing,Agents, Photosensitizing,Effect, Photosensitizing,Effects, Photosensitizing
D017382	Reactive Oxygen Species	Molecules or ions formed by the incomplete one-electron reduction of oxygen. These reactive oxygen intermediates include SINGLET OXYGEN; SUPEROXIDES; PEROXIDES; HYDROXYL RADICAL; and HYPOCHLOROUS ACID. They contribute to the microbicidal activity of PHAGOCYTES, regulation of SIGNAL TRANSDUCTION and GENE EXPRESSION, and the oxidative damage to NUCLEIC ACIDS; PROTEINS; and LIPIDS.	Active Oxygen Species,Oxygen Radical,Oxygen Radicals,Pro-Oxidant,Reactive Oxygen Intermediates,Active Oxygen,Oxygen Species, Reactive,Pro-Oxidants,Oxygen, Active,Pro Oxidant,Pro Oxidants,Radical, Oxygen
D054833	Isoindoles	Benzopyrroles with the nitrogen at the number two carbon, in contrast to INDOLES which have the nitrogen adjacent to the six-membered ring.	Isoindole