Two groups of tick-borne encephalitis (TBE) virus strains were studied: Group 1, 5 strains isolated from patients with chronic TBE with progressive course, Group 2, 13 strains isolated from residents of an endemic locality, with chronic diseases of the CNS (amiotrophic lateral sclerosis, epidemic encephalitis, polyoencephalomyelitis, syringomyelia, etc.). Strains of both groups belong to two serotypes of TBE virus: mid-Siberian and Transbaikal (synonym Aina/1448) and eastern. Group 1 strains were heterogeneous in their virulence, immunogenic and surface properties of the virions. The latter characteristic was demonstrated in studies of elution from macropore glass and sensitivity of hemagglutinin to the effect of detergents (Bridge-96, Tween-80). Eight of 13 Group 2 patients had concurrent diseases (tuberculosis, toxoplasmosis, tumors, etc.). Streptomycin was demonstrated to activate asymptomatic infection with TBE virus in hamsters. It is assumed that isolation of TBE virus from Group 2 patients could be due to activation of persistent infection under the effect of concurrent diseases and drugs.
To investigate the role of rat brain cortex Na+, K(+)-ATPase plasma membrane microenvironment in ethanol effect in vitro on membrane the sensitivity of enzyme activity to alcohol was studied under membrane perturbation induced by sodium dodecyl sulfate. The increase of enzyme sensitivity to detergent inactivation in the presence of high ethanol concentrations and to alcohol inhibition after modification by Ds-Na was revealed. It is supposed that Na+, K(+)-ATPase sensitivity to ethanol is dependent on structural state of protein microenvironment in accordance with assumed differences in structural organization of the boundary lipids of the neuronal enzyme isoforms.
The collagen prolyl 4-hydroxylases (P4Hs, EC ) play a critical role in the synthesis of the extracellular matrix. The enzymes characterized from vertebrates and Drosophila are alpha(2)beta(2) tetramers, in which protein disulfide isomerase (PDI) serves as the beta subunit. Two conserved alpha subunit isoforms, PHY-1 and PHY-2, have been identified in Caenorhabditis elegans. We report here that three unique P4H forms are assembled from these polypeptides and the single beta subunit PDI-2, both in a recombinant expression system and in vivo, namely a PHY-1/PHY-2/(PDI-2)(2) mixed tetramer and PHY-1/PDI-2 and PHY-2/PDI-2 dimers. The mixed tetramer is the main P4H form in wild-type C. elegans but phy-2-/- and phy-1-/- (dpy-18) mutant nematodes can compensate for its absence by increasing the assembly of the PHY-1/PDI-2 and PHY-2/PDI-2 dimers, respectively. All three of the mixed tetramer-forming polypeptides PHY-1, PHY-2, and PDI-2 are coexpressed in the cuticle collagen-synthesizing hypodermal cells. The catalytic properties of the mixed tetramer are similar to those of other P4Hs, and analogues of 2-oxoglutarate were found to produce severe temperature-dependent effects on P4H mutant strains. Formation of the novel mixed tetramer was species-specific, and studies with hybrid recombinant PHY polypeptides showed that residues Gln(121)-Ala(271) and Asp(1)-Leu(122) in PHY-1 and PHY-2, respectively, are critical for its assembly.
Persistence of the brain and kidney Na+,K(+)-ATPase isozymes to SDS inactivation under different time and temperature conditions of microsome extraction with the detergent was compared. In contrast to enzyme preparations from medulla oblongata the higher sensitivity of the Na+,K(+)-ATPase alpha-isoform (in comparison to alpha +) to SDS inactivation accompanied by its, at least, partial removal from the membrane was found in the preparations from cerebral cortex. This difference in the sensitivity to SDS was eliminated after extraction of microsomes with the detergent at 37 degrees C. The interpretation of the results is based on the assumed differences in the structural organization of the boundary lipids of the neuronal Na+,K(+)-ATPase catalytic subunit isoforms.
5-Lipoxygenase (5-LO) (126.96.36.199) demonstrates its activity in membrane-associated state. A system in vitro with increasing quantity of mixed micelle of nonionic detergent Lubrol PX and substrate--linoleic acid (LA) was used for understanding of 5-LO catalytic activity mechanism, which depends on the membrane environment. Physical parameters of micelles with molar ratio LA-Lubrol PX = 0.3:1 and micelles with 5-LO inhibitor--linoleyl hydroxamic acid (LHA), LA and Lubrol PX (0.03:0.3:1) were characterized by gel-filtration method on Sephadex G-200. It was determined, that Stock's radii were 4.83-5.79 nm for micelles with total LA--50-2000 microM and average molecular mass--177 000-212 000 Da. The presence of 10 microM LHA has no influence on physical parameters of the system. Influence of LHA on kinetic parameters of LA oxidation reaction catalized by potato tubers 5-LO in characterized mixed micelle system was also studied. Substrate dependences curves of 5-LO LA oxidation steady-state rates under conditions of the mixed micelle with ratio LA-lubrol PX = 0.3:1, LHA-LA-Lubrol PX = 0.03:0.3:1 and LHA-LA-Lubrol PX = 0.12:0.3:1 were typical of the substrate inhibition. The presence of inhibitor had no effect on the number of additional substrate molecules--LA which contact with enzyme-substrate complex and decreased V(max) essentially. To predict further inhibitor transformation in the cell the influence of 13-hydroperoxy- and 13-hydroxy LHA on potato tubers 5-LO and porcine leucocyte 12-LO was investigated. It was established that LHA oxidized forms displayed as no less effective inhibitors of the analyzed enzymes; 13-hydroperoxy LHA efficiency increased by an order (IC50 was 0.7 microM) for 12-LO. The possibility of 5-LO to oxidize inhibitor LHA under 50 microM phosphatidic acid at pH 5.0 was demonstrated.
Five grams of seafood products were inoculated with one to 500 viable or 10(9) heat-killed cells of Listeria monocytogenes. The presence of the pathogen was detected by the polymerase chain reaction (PCR) with primers specific for fragments of the listeriolysin O (hly) gene (two sets) and for the invasion-associated protein (iap) gene (one set). For DNA preparation, boiling, either alone or in combination with lysozyme and proteinase K treatment, was not always sufficient to lyse L. monocytogenes, while treatment with Triton X-100 produced consistently good DNA suitable for amplification. To avoid false-negative and false-positive results, 48 h incubations were necessary and a subculturing step after an initial 24 h incubation greatly improved the results. The primers that amplified regions of the listeriolysin O gene gave clearer and stronger products than primers for the invasion-associated protein gene. Using this method we were able to detect one to five L. monocytogenes cells in 5 g of product in a total of 55 h.
A glucuronyltransferase involved in glucuronoxylan biosynthesis was obtained from the epicotyls of 1-week-old etiolated pea (Pisum sativum var. Alaska) seedlings and was solubilized in Triton X-100, a non-ionic detergent. The enzyme was inactivated by SDS and inhibited by Derriphat 160 and cholic acid. The enzyme was active in the presence of NN-dimethyldodecylanium-N-oxide, but was not solubilized by it. The stimulatory effect of UDP-D-xylose on the particulate and solubilized enzymes was the same, but the optimum Mn2+ concentration was lower for the solubilized enzyme, and the product formed by the solubilized enzyme has altered structure and solubility properties. Gel filtration of the solubilized enzyme on Sepharose CL-6B permitted partial separation of the stimulatory effect of UDP-D-xylose from the activity in the absence of UDP-D-xylose. The solubilized enzyme was more stable than the particulate enzyme and could be stored for 2 weeks at -20 degrees C without loss of activity.
LH receptors were solubilized from human corpora lutea in phosphate-buffered saline containing 1% Triton X-100, 20% glycerol, and protease inhibitors. The presence of 20% (vol/vol) glycerol was necessary for quantitative preservation of [125I]hCG-binding activity in detergent solution. The solubilized receptors were stable for several weeks at -20 C and at -80 C and for at least 18 h at 4 C. Binding of [125I]hCG to the soluble LH receptors was time and temperature dependent and varied linearly with the amount of soluble protein. Equilibrium binding studies revealed a single class of high affinity [125I]hCG-binding sites with an equilibrium dissociation constant (Kd) of 4.3 x 10(-10) mol/L (at 20 C). The molecular size of the human LH receptors was analyzed by ligand blotting. Solubilized receptors were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions and transferred to nitrocellulose. Incubation of the protein blot with [125I]hCG to the 85/90K mol wt species was inhibited by unlabeled hCG. These results indicate that LH receptors can be solubilized in nonionic detergent while maintaining their hormone-binding activity and demonstrate that the receptors contain 85/90K hormone-binding species.