Purification and characterization of Aspergillus ficuum endoinulinase.
(57/37801)
Endoinulinase from Aspergillus ficuum, which catalyzes the hydrolysis of inulin via an endo-cleavage mode, was purified by chromatography from Novozym 230 as a starting commercial enzyme mixture on CM-Sephadex and DEAE-Sepharose, and by preparative electrophoresis under native conditions. The enzyme was estimated to be pure on the basis of its I/S ratio, whose value was infinite in our assay conditions. Two forms separated by using this method. SDS gel electrophoresis showed the two purified forms to respectively exhibit molecular weights of 64,000 +/- 500 and 66,000 +/- 1,000. The results of deglycosylation indicated that the two forms were originally the same protein but with different sugar contents. A molecular weight of 54,800 +/- 1,500 was found by gel filtration of the native enzyme, indicating the native functional protein to be a monomer. The enzyme showed nearly absolute substrate specificity towards inulin and inulooligosaccharides, and acted via an endo-attack to produce mainly inulotriose during the late stage of the reaction. The apparent Km and Vmax values for inulin hydrolysis were 8.1 +/- 1.0 mM and 773 +/- 60 U/mg, respectively. The internal peptides of the enzyme showed sequence homology to the endoinulinase of Penicillium purpurogenum. (+info)
Effects of truss mattress upon sleep and bed climate.
(58/37801)
The purpose of this study was to examine the effects of a truss mattress upon sleep and bed climate. The truss mattress which has been designed to decrease the pressure and bed climate humidity was tested. Six healthy female volunteers with a mean age of 23.3 years, served as subjects. The experiment was carried out under two conditions: a truss mattress (T) and a futon (F) (Japanese bedding). The ambient temperature and relative humidity were controlled at 19-20 degrees C, and RH 50-60% respectively. Sleep was monitored by an EEG machine and the rectal temperature, skin temperature and bed climate were also measured continuously. Subjective evaluations of bed and sleep were obtained before and after the recording sessions. No significant difference was observed in the sleep parameters and time spent in each sleep stage. Rectal temperature was significantly lower in T than F. Although there was no significant difference in bed climate over the T/F, the temperature under T/F was significantly higher in T. No significant difference was observed in subjective sleep evaluation. The subjective feeling of the mattress was significantly warmer in F than T before sleep. These results suggest that although T does not disturb the sleep parameters and the bed climate is maintained at the same level as with F, it may affect rectal temperature which can be due to low thermal insulation. (+info)
Coupling of coat assembly and vesicle budding to packaging of putative cargo receptors.
(59/37801)
COPI-coated vesicle budding from lipid bilayers whose composition resembles mammalian Golgi membranes requires coatomer, ARF, GTP, and cytoplasmic tails of putative cargo receptors (p24 family proteins) or membrane cargo proteins (containing the KKXX retrieval signal) emanating from the bilayer surface. Liposome-derived COPI-coated vesicles are similar to their native counterparts with respect to diameter, buoyant density, morphology, and the requirement for an elevated temperature for budding. These results suggest that a bivalent interaction of coatomer with membrane-bound ARF[GTP] and with the cytoplasmic tails of cargo or putative cargo receptors is the molecular basis of COPI coat assembly and provide a simple mechanism to couple uptake of cargo to transport vesicle formation. (+info)
Replication-dependent marking of DNA by PCNA facilitates CAF-1-coupled inheritance of chromatin.
(60/37801)
Chromatin assembly factor 1 (CAF-1) is required for inheritance of epigenetically determined chromosomal states in vivo and promotes assembly of chromatin during DNA replication in vitro. Herein, we demonstrate that after DNA replication, replicated, but not unreplicated, DNA is also competent for CAF-1-dependent chromatin assembly. The proliferating cell nuclear antigen (PCNA), a DNA polymerase clamp, is a component of the replication-dependent marking of DNA for chromatin assembly. The clamp loader, replication factor C (RFC), can reverse this mark by unloading PCNA from the replicated DNA. PCNA binds directly to p150, the largest subunit of CAF-1, and the two proteins colocalize at sites of DNA replication in cells. We suggest that PCNA and CAF-1 connect DNA replication to chromatin assembly and the inheritance of epigenetic chromosome states. (+info)
Bacteriophage SPO1 development: defects in a gene 31 mutant.
(61/37801)
SPO1 temperature-sensitive mutant ts14-1, located in cistron 31, has a DD (DNA synthesis-delayed) phenotype at 37 degrees C and produces progeny in a stretched program. At 44 degrees C it behaves as a DO (DNA synthesis-defective) mutant and shuts off the viral RNA synthesis about 10 min after infection. The thermal sensitivity of this mutant is due to the inactivity of gp-31 (the product of gene 31) at 44 degrees C. However, gp-31 is synthesized at that temperature and partly recovers its activity at 37 degrees C. Only 5 min at the permissive temperature is enough to trigger the continuation of the phage program and to produce progeny. The partial defect at 37 degrees C and the expansion of the middle program together with the pleiotropic defects at the nonpermissive temperature could be suitable for the study of the controls involved in bacteriophage development. (+info)
Evidence that the neck appendages are adsorption organelles in Bacillus subtilis bacteriophage phi29.
(62/37801)
A mutant of Bacillus subtilis unable to adsorb phage phi29 efficiently has been isolated. This mutant can be infected by host range mutants of the phage. Since the host range mutations map in cistron 12, which codes for neck appendage protein, this would tend to confirm that these organelles are involved in viral adsorption. (+info)
Translocation of ornithine decarboxylase to the surface membrane during cell activation and transformation.
(63/37801)
Ornithine decarboxylase (ODC) is highly up-regulated in proliferating and transforming cells. Here we show that upon induction, an initial cytosolic increase of ODC is followed by translocation of a fraction of the enzyme to the surface membrane. ODC membrane translocation is mediated by a p47(phox) membrane-targeting motif-related sequence, as indicated by reduced ODC activity in the membrane fraction of cells treated with a competing, ODC-derived (amino acids 165-172) peptide, RLSVKFGA, which is homologous to the p47(phox) membrane-targeting sequence. p47(phox) membrane translocation is known to be dependent on the phosphorylation of the targeting motif. Analogously, overexpressed ODC.S167A, a mutant ODC lacking the putative phosphorylation site Ser67, is unable to move to the surface membrane. Cells blocked with the RLSVKFGA peptide showed defective transformation, indicating that the motif-mediated translocation of ODC is prerequisite to its biological function. Constitutive targeting of ODC to the membrane using a plasmid encoding the chimeric protein, wild-type ODC with C-terminal linkage to the farnesylation motif of K-ras, caused impaired cytokinesis with an accumulation of polykaryotic cells. Impaired cytokinesis confirms that ODC is involved in mitotic cytoskeletal rearrangement events and pinpoints the importance of relevant membrane targeting to its physiological function. (+info)
Characterization of a leukotriene C4 export mechanism in human platelets: possible involvement of multidrug resistance-associated protein 1.
(64/37801)
Platelets express leukotriene (LT) C4 synthase and can thus participate in the formation of bioactive LTC4. To further elucidate the relevance of this capability, we have now determined the capacity of human platelets to export LTC4. Endogenously formed LTC4 was efficiently released from human platelets after incubation with LTA4 at 37 degrees C, whereas only 15% of produced LTC4 was exported when the cells were incubated at 0 degrees C. The activation energy of the process was calculated to 49.9 +/- 7.7 kJ/mol, indicating carrier-mediated LTC4 export. This was also supported by the finding that the transport was saturable, reaching a maximal export rate of 470 +/- 147 pmol LTC4/min x 10(9) platelets. Furthermore, markedly suppressed LTC4 transport was induced by a combination of the metabolic inhibitors antimycin A and 2-deoxyglucose, suggesting energy-dependent export. The presence in platelets of multidrug resistance-associated protein 1 (MRP1), a protein described to be an energy-dependent LTC4 transporter in various cell types, was demonstrated at the mRNA and protein level. Additional support for a role of MRP1 in platelet LTC4 export was obtained by the findings that the process was inhibited by probenecid and the 5-lipoxygenase-activating protein (FLAP) inhibitor, MK-886. The present findings further support the physiological relevance of platelet LTC4 production. (+info)