Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00080 (Leaf)
 21,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A levansucrase was demonstrated in the growth medium and in association with the cell surface of Actinomyces viscosus. The amount of enzyme produced relative to cell density is not significantly affected by the growth conditions. Sugar alcohols inhibit growth of the cells. The levansucrase hydrolyzes sucrose to produce free glucose and levan; some free fructose is also formed. There is no requirement for cofactors. The Km for sucrose is 12 mM. A variety of heavy metal ions and two disaccharides, lactose and cellobiose, inhibit the enzyme. The levansucrase was purified to homogeneity and has a specific activity of 90 micronmol of glucose release per min per mg. The enzyme has a molecular weight of 220,000 and is composed of subunits of molecular weight 80,000. The levan product contains both beta(2 leads to 1) and beta(2 leads to 6) linkages. The enzyme remains tightly bound to the levan product, resulting in the formation of high-molecular-weight polymer on the order of 10(8) daltons. The possible role of the levan and levansucrase of A. viscosus in the pathogenesis of periodontal disease is discussed.
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PMID:Levan and levansucrase of Actinomyces viscosus. 1 93

Freeze-drying of highly purified dextranse from Penicillium funiculosum and Fusarium solani was accompanied by 90% losses of enzyme activity and solubility. Many carbohydrates were tested as stabilizers, e.g. glucose, maltose, lactose, polyglucine, dextranase hydrolyzate of polyglucine as well as mannitol and ammonium sulfate. Polyglucine, its hydrolyzate, and glucose proved most effective stabilizers. The stabilizing effect of polyglucine hydrolyzate of dextranase during its heating and freeze-drying was compared. The effective concentration of the stabilizer during freeze-drying was 10 times lower than during heating.
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PMID:[Stabilization of dextranase from Penicillium funiculosum and Fusarium solani during heating and freeze-drying]. 53 15

An easy, rapid and economic two-step procedure is described for the detection of Salmonella/Shigella. In the first step the susceptibility of suspected colonies for the phage O-1 of FELIX and CALLOW is tested. Positive cultures are serologically confirmed. The test is performed on Triple Sugar Iron Agar and lasts 4-6 hrs. Phage negative cultures which are lactose- and sucrose negative are tested for lysine decarboxylase and, if Shigella is possible (i.e. in human material on primary plates), for indol production and motility in a semisolid tryptophane agar. Of 22880 Salmonella straine 21977, i.e. 96.1% were phage-sensitive. Strains belonging to certain O-groups (OE) or species are lysed at a lower percentage. However, since they are lysine decarboxylase positive they are not lost and can be submitted to a serological examination.
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PMID:An economic and rapid diagnostic procedure for the detection of salmonella/shigella using the polyvalent salmonella phage O-1. 63 6

Enzyme IIlac, the membrane-bound component of the lactose phosphotransferase system of Staphylococcus aureus, catalyzes the phosphorylation-transport reaction below: (see article). (The sugar can be lactose or one of its analogs.) The effects of the non-ionic detergents Triton X-100, Brij 35, and Tween 40 on the activity of Enzyme IIlac were studied. Especially striking effects were observed using Triton X-100, a detergent previously used to solubilize and isolate this enzyme. A systematic study of Triton effects over a range of concentrations and temperatures demonstrated three aspects of Triton-membrane interaction. At 0.1% Triton and 25 degrees C Enzyme IIlac is activated, but remains particulate. At 0.5% Triton and 0.5% Triton and 37 degrees C, it is rapidly and irreversibly inactivated. Sugar substrates and inhibitory sugar analogs protect Enzyme IIlac against inactivation; the effect is specific for beta-galactosides. The other substrate of Enzyme IIlac, phospho-Factor IIIlac, does not affect Triton inactivation, and the product analog galactose 6-phosphate slightly enhances the inactivation rate.
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PMID:Irreversibel inactivation of the membrane-bound enzyme IIlac of the lactose phosphotransferase system of Staphylococcus aureus by triton X-100 and protection by substrates. 83 39

The melB gene coding for the melibiose carrier of Klebsiella pneumoniae was cloned and sequenced. There were two potential translation initiation sites. It was predicted that the melibiose carrier consists of 471 (or 467) amino acid residues. Seventy-eight percent of the 471 amino acids were identical to the Escherichia coli melibiose carrier. Sugar transport characteristics were studied using an E. coli mel- mutant expressing cloned K. pneumoniae melB gene. Accumulation of melibiose via the K. pneumoniae melibiose carrier was not stimulated by adding NaCl or LiCl which stimulates melibiose accumulation via the E. coli melibiose carrier. Lactose was accumulated only in the presence of LiCl. TMG (methyl-1-thio-beta-D-galactopyranoside) was accumulated in the absence of added NaCl or LiCl. The accumulation was stimulated by LiCl but not by NaCl. Rapid H+ uptake was observed when melibiose or TMG was added to cell suspensions. These results suggest that the preferred cation couplings via K. pneumoniae melibiose carrier are H(+)-melibiose, Li(+)-lactose, and H+/Li(+)-TMG. This coupling spectrum is quite different from that of the E. coli melibiose carrier. It is of special interest that the K. pneumoniae melibiose carrier seems to be lacking the ability to recognize Na+ which is a preferred coupling cation of the E. coli melibiose carrier for all known sugar substrates. Further investigation of these two carriers may give us insight into the Na+ recognition site.
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PMID:Primary structure and characteristics of the melibiose carrier of Klebsiella pneumoniae. 133 36

Oral streptococci vary in their susceptibility to salivary agglutinin-mediated aggregation. To understand the molecular basis of this specificity, the structure and function of receptors for agglutinin from Streptococcus mutans KPSK2 (MSL-1) and Streptococcus sanguis M5 (SSP-5) were compared. Immunological screening of an S. mutans KPSK2 genomic DNA library yielded two identical clones expressing a streptococcal protein that co-migrated with a 220 kDa peptide in SDS extracts from this organism. This protein inhibited agglutinin-mediated aggregation of S. mutans KPSK2 in a dose-dependent manner. The MSL-1 gene is homologous to the S. mutans SpaP and pac genes although single base substitutions alter several amino acids. MSL-1 is also similar to the agglutinin receptor (SSP-5) cloned from S. sanguis M5. All three proteins, MSL-1, P1, and SSP-5 share at least one epitope since monoclonal and polyclonal anti-SSP-5 antibodies react with both MSL-1 and P1. However, other monoclonal antibodies are specific for SSP-5 and appear to react with a peptide domain exhibiting little homology to MSL-1 or P1. Sugar inhibition studies showed that agglutinin-mediated aggregation of S. mutans KPSK2 was most potently inhibited by fucose and lactose. Sialic acid, a potent inhibitor of S. sanguis aggregation, had no effect on the interaction of agglutinin with S. mutans KPSK2. These results suggest that while the MSL-1 and SSP-5 proteins are genetically and immunologically related, their specificity for binding sites on agglutinin differs.
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PMID:Comparison of Streptococcus mutans and Streptococcus sanguis receptors for human salivary agglutinin. 170 78

The Escherichia coli lactose carrier is an energy-transducing H+/galactoside cotransport protein which strictly couples sugar and proton transport in 1:1 stoichiometry. Here we describe five lactose carrier mutants which catalyze "uncoupled" sugar-independent H+ transport. Symptoms similar to uncoupling by a proton ionophore have been observed in cells expressing these mutant carriers. The mutations occur at two separate loci, encoding substitutions either for alanine 177 (valine) or tyrosine 236 (histidine, asparagine, phenylalanine, or serine). Compared to the parent, cells expressing the valine 177 carrier grew slowly on minimal media with glucose as carbon source. When washed cells were incubated in the absence of added sugars the mutant showed a reduced protonmotive force compared with the parent. Addition of either thiodigalactoside or alpha-p-nitrophenylgalactoside reduced the defect in protonmotive force. Sugar-independent H+ entry rate into cells expressing either the normal carrier or the Val-177 mutant were measured directly using the pH electrode. Following sudden acidification of the external medium (by either oxygen-pulse or acid-pulse) protons entered more rapidly into cells expressing the Val-177 carrier. This novel sugar-independent mode of H+ transport probably depends on an acquired capacity of the Val-177 carrier to bind the transported proton with higher than normal affinity in a transition state involving the binary carrier/H+ complex.
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PMID:Characterization of Escherichia coli lactose carrier mutants that transport protons without a cosubstrate. Probes for the energy barrier to uncoupled transport. 216 39

The formation of the mutagenic imidazoquinoxalines (MeIQx, DiMeIQx) was studied using a modification of a previous model system. Creatine or creatinine (0.9 mmole) was heated together with glycine (0.9 mmole) and various sugars (0.45 mmole) dissolved in diethylene glycol and water (3 ml, 5:1) for up to 15 min at 180 degrees C. This system produced the same amount of mutagenicity after 10 min at 180 degrees C as a previous one during 2 h of reflux boiling at 128 degrees C. MeIQx (4 nmole/mmole creatin(in)e) was the major mutagen produced together with minor amounts of DiMeIQx, both 4,8- and 7,8-DiMeIQx according to HPLC-MS. A few other mutagenic peaks were also separated on HPLC, but they were not identified. Varying the concentration (0-2.4 mmole) and type of monosaccharides and disaccharides greatly affected the yields of all the mutagenic compounds. Sugar in molar amounts lower than the creatin(in)e concentration increased the yield until an optimum was reached. In higher concentrations the formation of all the mutagens was markedly reduced. The same was found for glucose, fructose, sucrose, and lactose, though the monosaccharides showed the most pronounced inhibitory effects. The inhibition of the formation of the mutagenic compounds by an excess of sugars is proposed to be an effect of Maillard reaction products, which may block the formation of imidazoquinoxalines by attacking creatine. Support for this mechanism is given by data showing a lower recovery of unreacted creatine with increasing concentration of glucose and also by an inhibitory effect on the formation of these mutagens after adding a typical Maillard reaction product, 5-hydroxymethyl-2-furfural.
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PMID:Effects of monosaccharides and disaccharides on the formation of food mutagens in model systems. 237 62

Fourier-transform infrared spectroscopy was used to characterize the interaction of stabilizing carbohydrates with dried proteins. Freeze-drying of trehalose, lactose, and myo-inositol with lysozyme resulted in substantial alterations of the infrared spectra of the dried carbohydrates. In the fingerprint region (900-1500 cm-1), there were large shifts in the frequencies of bands, a decrease in absorbance, and a loss of band splitting. These effects mimic those of water on hydrated trehalose. Bands assigned to hydroxyl stretching modes (around 3350 cm-1) were decreased in intensity and shifted to higher frequencies in the presence of the protein. In complementary experiments, it was found that dehydration-induced shifts in the positions of amide I and amide II bands for lysozyme could be partially and fully reversed, respectively, when the protein was freeze-dried in the presence of either trehalose or lactose. In addition, the carboxylate band, which was not detectable in the protein dried without the sugar, was apparent when these sugars were present. myo-Inositol was less effective at shifting the amide bands, and the carboxylate band was not detected in the presence of this carbohydrate. Also tested was the concentration dependency of the carbohydrates' influence on the position of the amide II band for dried lysozyme. The results showed that the ability of a given concentration of a carbohydrate to shift this band back toward the position noted with the hydrated protein coincided, at least in the extreme cases, with the capacity of that same level of carbohydrate to preserve the activity of rabbit skeletal muscle phosphofructokinase during freeze-drying.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:An infrared spectroscopic study of the interactions of carbohydrates with dried proteins. 252 52

1. Sugar best single chorda tympani nerve fiber of rat and hamster were tested with six sugars. 2. Fibers were selected for this experiment, only if they responded to 1.0 M sucrose or 1.0 M maltose and they responded poorly to 0.1 M NaCl. 3. In rat, some single fibers gave larger responses to maltose than to sucrose, while in hamster nearly all nerve fibers responded best to sucrose. 4. The order of effectiveness of sugars was maltose greater than fructose greater than or equal to lactose greater than sucrose greater than glucose greater than galactose in rat and sucrose greater than fructose greater than or equal to glucose greater than or equal to galactose greater than maltose greater than lactose in hamster.
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PMID:Sugar best single chorda tympani nerve fiber responses to various sugar stimuli in rat and hamster. 257 46


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