Instead of aqueous solutions, universally recognized in enzymology, ternary systems of the waterlorganic solvent/surfactant type are suggested as liquid-crystalline media for enzymatic reactions. Two systems, water/ octane/Aerosol OT and water/cyclohexane/Brij 96, have been used to solubilize acid and alkaline phosphatases and peroxidase. The enzymes under study do function in liquid-crystalline mesophases having lamellar, cylindrical (reversed hexagonal) and ball-shaped (reversed cubic) packing of the surfactant molecules. A significant result is that the phase transition from one liquid-crystalline structure to another entails, as a rule, a reversible change in the catalytic activity of the solubilized enzyme.There is no doubt that the lipid bilayer forms the framework of biological membranes and provides the barrier function [I]. Recently, however, a clear understanding has been achieved of the role that might be played in membranes by lipid polymorphism and local transitions between lamellar (bilayer) and hexagonal lipid phases [2 -171. The topic under discussion is the formation in membranes of hexagonally packed cylinders, in which the polar head groups of lipid molecuies line the narrow channel filled with water. It also seems possible that, inside the lipid bilayer, smaller associates of lipid molecules spring up, almost spherical and built like reversed micelles (lipid particles). The driving forces of such rearrangements in membranes and a possible biological role of non-bilayer structures were discussed in some recent reviews [14, 15,[18][19][20][21][22].These new ideas cause new enzymological problems since the overwhelming majority of enzymes in vivo function on the surface of biological membranes or inside them [23 -301. It is, therefore, important to elicit first whether enzymes can, in principle, possess catalytic activity if they are entrapped into microheterogeneous aggregates (of the types of lamellas, cylinders and/or ball-shaped micelles) built from lipid molecules. Second, whether the catalytic activity of the entrapped enzymes alters after the transition from one type of packing of lipid molecules to another.The problem of lipid dependence of enzymes has long been under discussion [31-401. As the chief regulatory factors (in addition to specific lipid-protein interactions, see for instance [41,42]), the microviscosity [35,39,401 Another regulatory factor might be the capacity of liquid crystals for polymorphism; for review, see monographs [18, 441. Indeed the structural rearrangement of the type : bilayer (L) e hexagonal phase (HI,) was recently found to influence the catalytic activity of some enzymes (phospholipases, phosphodiesterases, ATPase and manosyltransferase) entrapped into proteoliposomes [lo, 45-49] '.In our opinion, a handier way to solve the membranological problems of this kind derives from the solubilization of enzymes in microheterogeneous media of the water/organic solvent/surfactant type [22]. The point is that the amphiphilic molecules of surfactants in water/organ...

Using reversed micelles of surfactants solvated by water-organic cosolvent mixtures as a matrix for enzyme entrapping, it is possible to iix the highly reactive g-chymotrypsin form. The reactivity of a-chymotrypsin towards nonspecific substrates increases to the extent comparable with that observed in reactions involving specific substrates.a-Chymot~ps~n; Conformation; Solvated reversed micelle; Substrate specificity

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We studied the effect of peripheral μ- and κ-opioid receptor agonists (not crossing the bloodbrain barrier) on locomotor activity and metabolism in rats after acute administration of ethanol. Intraperitoneal injection of ethanol in a single dose of 2 g/kg had a strong depressive effect manifested in a decrease in horizontal locomotor activity and suppression of metabolism. μ-Opioid receptor agonist DAMGO and κ-opioid receptor agonist ICI 204,448 partly abolished the effect of ethanol on locomotor activity of rats. ICI 204,448 was most potent in this respect. In contrast to μ-opioid receptor agonist DAMGO, κ-opioid receptor agonist ICI 204,448 prevented metabolism suppression induced by ethanol. Our results indicate that ICI 204,448 significantly inhibits the depressive effect of ethanol. DAMGO showed only partial effectiveness under these experimental conditions.

This paper discloses for the first time the effects of the gas phase (GP) and the tar of cigarette smoke on lipid peroxidation (LPO) and on the structure of different lipid regions in liposomes. The LPO development was analysed in terms of the total unsaturation of lipids (double-bond, DB, content) and the formation of dienic conjugates (DC), ketodienes (KD), and malonic dialdehyde (MDA). As expected, the exposure of liposomes to either the GP or the tar led to a significant decrease in the DB content. However, the formation of oxidation products revealed different dynamics: MDA generation was inhibited, while the formation of DC and KD increased during the first few hours of the LPO development followed by its inhibition. The smoke constituents exhibited opposite effects on the structure of the lipid bilayer of liposomes: the GP markedly enhanced the microviscosity of liposomal membranes, whereas the tar caused a drastic lowering of microviscosity.

High activities of prolyl endopeptidase and dipeptidylpeptidase IV in the striatum and of prolyl endopeptidase in the frontal cortex were recorded in rats with stress-induced depression-like state (behavioral despair) developed in the Porsolt forced swimming test. Acute injection of benzyloxycarbonyl-methionyl-2(S)-cyanopyrrolidine (prolyl endopeptidase noncompetitive synthetic inhibitor) in a dose of 1 mg/kg prevented the development of behavioral despair and the increase of prolyl endopeptidase and dipeptidylpeptidase IV activities in the brain structures. In a dose of 2 mg/kg prolyl endopeptidase inhibitor did not modify the development of behavioral despair, but prevented the increase of prolyl endopeptidase and dipeptidylpeptidase IV activities in the striatum.