Variação nos hábitos alimentares da mosca de estábulos Stomoxys calcitrans L

During the course of a study on the behaviour, of Stomoxys calcitrans a research on the feeding habits of this fly was carried out. A total of 27l4 flies were caught in three poultry ranches from Araucária, Paraná. The source of the flie's sucked blood has been established by precipitin test. . The results showed that although almost all the flies usually feed mammal blood, some of them gave positive precipitin test for birds blood. Although all flies were caught on poultry ranches, none had feed on chickens but 2,7 percent of the total had feed on ducks, 0.7 percent on geese and 0.37 percent on turkeys.

Purification and general properties of L-fucose dehydrogenase from Pullularia pullalans

An inducible L-fucose dehydrogenase from the yeast-like fungus Pullularia pullulans was purified and studied. The enzyme catalyses the oxidation of L-fucose to L-fuconic acid possibly throught its unstable L-funcono-lactone. the enzyme was purified to hemogeneity by a sequence of protamine sulfate treatment, ammonium sulfate fractionation, gel filtration on Sephadex G-100, and DEAE-cellulose chromatography. This sequence resulted in an 87 fold purification. The apparent molecular weight determined by gel filtration and SDS polyacrilamide gel electrophoresis was 40 000. the dehydrogenase was NAD-especific and showed a high sugar substrate specificity. Of several D-and L-aldoses tested only L-fucose, L-galactose and-arabinose served as substrates. The maximum velocity for the reaction was at 33- and pH 10.5. Under these conditions, the Km values, and D-arabinose, respectively. The enzyme was strongly inhibited by thiol reagents, heavy metal ions, and was not particularly stable. At 4- it rapidly los activity, but remained active for two months when maintained at -20-. The enzyme has been used to quantativate L-fucose

UDP-N-Acetyl-D-Glucosamine biosynthesis in coffee leaves

With the purpose of elucidating the pathway of uridine-diphospate-N-acetyl-D-glucosamine formation in coffee plants, studies. These studies showed that UDP-N-acetyl-D-glucosamine is formed from fructose 6-phosphate and glutamine by a series of the following reactions: a) D-Glucosamine 6-P + acetylCoA N-acetul-D-Glucosamine 6-P ñ CoA c) N-Acetyl-D-glucosamine 6-P N-acetyl-D-glucosamine 1-P d) N-Acetyl-D-glucosamine 1-P + UTP UDP-N-acetyl-D-glucosaamine + PP Glucosamine 6-phospate was either obtained by its directly phosphorylation by ATP and hexokinase. Deaminase and phospatase activities were also determined

Partial purification and some properties of beta-phosphoglucomutase from Lactobacillus brevis.

A phosphoglucomutase (beta-phosphoglucomutase) specific for beta-glucose 1-phosphate, which catalyzes the beta-glucose 1-phosphate:glucose 6-phosphate interconversion, was 560-fold purified from Lactobacillus brevis strain L6. The isoelectric point of beta-phosphoglucomutase was 3.8 and it had an apparent molecular weight of 29,000 estimated by gel chromatography. The enzyme required a divalent cation (Mn2+ greater than Mg2+ greater than Ni2+ greater than Co2+) and beta-glucose 1,6-bisphosphate for activity. The equilibrium constant Ke for the reaction beta-D-glucose 1-phosphate in equilibrium D-glucose 6-phosphate at 30 degrees C and pH 6.7 is 18.5. beta-phosphoglucomutase had a pH optimum between 6.3 and 6.8 and appeared to be quite specific: alpha-glucose 1-phosphate, alpha- or beta-galactose 1-phosphate and alpha- or beta-N-acetylglucosamine 1-phosphate did not substitute for beta-glucose 1-phosphate. Double reciprocal plots of the data from initial velocity studies at five beta-glucose 1-phosphate concentrations (10 to 100 microM) and four beta-glucose 1,6-bisphosphate concentrations (0.125 to 1.0 microM) showed that the apparent Michaelis constants for beta-glucose 1-phosphate and beta-glucose 1,6-bisphosphate were related to the concentrations of beta-glucose 1,6-bisphosphate and beta-glucose 1-phosphate, respectively, in such a way as to suggest a ping-pong mechanism. The same conclusion was obtained when substrate-velocity relationships were investigated at fixed ratio of both substrates: the Lineweaver-Burk plots showed linear lines and no parabolic ones. The "true" Km for beta-glucose 1-phosphate and beta-glucose 1,6-bisphosphate were found to be about 12 and 0.8 microM, respectively.

Muscle D-glyceraldehyde-3-phosphate dehydrogenase from Caiman sp. II New data for enzyme characterization.

Muscle GPDH from Caiman sp. was activated by dithioerythritol and 2-mercaptoethanol. Maximal activation was obtained with the reducing agent at 10mM final concentration. The binding of NAD to the apoenzyme occurs at four sites per tetramer, but ligand affinity seems to be heterogeneous. Incubation of the holo or the apoenzyme with NADH at 37 degrees C caused inactivation of the enzyme, with partial loss of SH-titrable groups. Incubation of the holo or the apoenzyme with G3P at 37 degrees C caused partial inactivation of the enzyme. The apoenzyme was demonstrated to be more stable than the respective holoenzyme, in the assay conditions used.

Purification and properties of the xylitol dehydrogenase from Pullularia pullulans.

Pullularia pullulans grown on D-xylose induces the synthesis of a xylitol dehydrogenase capable of oxidizing xylitol to D-xylulose in the presence of NAD according to the following reaction: Xylitol + NAD+ in equilibrium to D-xylulose + NADH + H+. Cells grown on D-glucose do not show appreciably xylitol dehydrogenase activity. However, synthesis of the enzyme begins when those cells were transferred to a liquid medium containing D-xylose. This evidence suggests that xylitol dehydrogenase is an induced enzyme. The purified xylitol dehydrogenase of Pullularia pullulans is quite specific for xylitol, unlike similar dehydrogenases from other sources, which attack a variety of polyols of variable chain length. This property makes the enzyme useful for the determination of xylitol, even in the presence of other polyols.

Induction and catabolite repression of L-rhamnose dehydrogenase in Pullularia pullulans.

The growth of Pullularia pullulans on L-rhamnose (6-deoxy-L-mannose) as the sole carbon source induces the synthesis of L-rhamnose dehydrogenase, a nicotinamide adenine dinucleotide-dependent enzyme that catalyzes the oxidation of the deoxy sugar to L-rhamnonolactone. The enzyme induction is inhibited by cycloheximide, suggesting de novo synthesis. The presence of d-glucose (0.2%) or D-galactose (0.2%) simultaneously with the inducer in the induction medium produced 50% repression of dehydrogenase synthesis, but no effect was detected with D-fructose and D-mannose at the same concentration. High levels of D-glucose (2%), under maximal catabolite repression conditions, produced a complete inhibition of enzyme synthesis.

L-Rhamnose dehydrogenase of pullularia pullulans.

Growth of Pullularia pullulans on L-rhamnose induces formation of L-rhamnofuranose dehydrogenase, whichreversibly converts L-rhamnofuranose to L-rhamnono-gamma-lactone with the concomitant reduction of NAD, but not of NADP. The dehydrogenase was purified 100-fold by MnCl(2) treatment...