Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The production of dextransucrase from Leuconostoc mesenteroides NRRL B-512F was stimulated 2-fold by the addition of 0.005% of calcium chloride to the medium; levansucrase levels were unaffected. Dextransucrase was purified by concentration and dialysis of the culture supernatant with a Bio-Fiber 80 miniplant, and by treatment with dextranase followed by chromatography on Bio-Gel A-Fm. A 240-fold purification, with a specific activity of 53 U/mg, was obtained. Contaminating enzyme activities of levansucrase, invertase, dextranase, glucosidase, and sucrose phosphorylase were decreased to non-detectable levels. Poly(acrylamide)-gel electrophoresis of the purified enzyme showed only two protein bands, both of which had dextransucrase activity. These bands also gave a carbohydrate stain, indicating that the dextransucrase could be a glycoprotein. Acid hydrolysis, followed by paper chromatography, of the purified enzyme showed that the major carbohydrate was mannose. Concanavalin A completely removed dextransucrase activity from solution, confirming the mannoglycoprotein character of the enzyme. Dextransucrase activity was not altered by the addition of 0.008-4 mg/ml of dextran, but its storage stability was increased by the addition of 4 mg/ml of dextran. As previously shown by others, the activity of dextransucrase was decreased by EDTA, and was restored by the addition of calcium ions. Zinc, cadmium, lead, mercury, and copper ions were inhibitory to various degrees.
 ...
PMID:Production, purification, and properties of dextransucrase from Leuconostoc mesenteroides NRRL B-512F. 10 66

Streptococcus mutans has been shown to produce extracellular invertase, dextransucrase, and levansucrase. The purpose of this work was to study the relative quantities of these enzymes in pure culture supernatant, and in samples from commonly used purification methods. The strain "Ingbritt" was selected because it is a well-defined human strain, available, and with well-known growth requirements. The samples were incubated with sucrose for the determination of free monohexoses, and the polysaccharide from ethanol precipitation was hydrolyzed as previously described. In cell supernatant the inversion effect exerted 75% of total sucrolytic power, the dextransucrase 20% and the levansucrase 5%. No method, tested in this work, could separate all the activities completely.
 ...
PMID:Combined extracellular sucrolytic enzyme power from a strain of Streptococcus mutans, and purification results. 28 69

Specific growth rates, growth yields, and the level and cellular distribution of three sucrose-metabolizing enzyme activities were determined for seven oral streptococci (Streptococcus mutans strains E49, BHT, 10449, SL-1, and LM-7, S. sanguis 10558, and S. salivarius 25975). Cultures were grown in a fermentor at pH 6 with either 20 mM glucose or 10 mM sucrose. Generation times varied between 21 and 70 min. Whereas some strains grew 10 to 50% more slowly with sucrose than with glucose, others did not. Growth was always logarithmic, and the growth yields were similar. Glcosyl transferase (EC 2.4.1.5) was largely extracellular; in sucrose cultures it was appreciably lower, but no major shift to a cell-associated form was found. In glucose cultures, the activity varied between 4 and 140 IU per 6-liter culture. The glucan formed was mostly or exclusively water insoluble. Glcosyl transferase was stimulated weakly (60% or less) by various dextrans. Fructosyl transferase (EC 2.4.1.10) was primarily extracellular (except in glucose cultures of S. salivarius) and varied between 0 and 337 IU/culture. In S. salivarius, the extracellular fructosyl transferase was induced by sucrose. In all S. Mutans cultures, the total fructosyl transferase activity was lower after growth with sucrose. All strains had extra- and intracellular invertase (EC 3.2.1.26) activity. Total levels varied between 210 and 3,500 IU/culture. Less extracellular activity was present in sucrose cultures. Only S. salivarius had appreciable activity in the cellular particulate fraction. Invertase activity was significantly higher than the combined glucosyl and fructosyl transferase activities in all cultures.
 ...
PMID:Occurrence and distribution of sucrose-metabolizing enzymes in oral streptococci. 97 54

Dental plaque material, collected from five subjects, was pooled, homogenised and sonicated. The cell-free extracts and the remaining plaque suspension were incubated with sucrose. Approximately 14 per cent of the total "sucrase" activity was found in the cell-free extracts after homogenisation, 46 per cent in the cell-free extracts after sonication and 40 per cent in the remaining plaque suspension containing cell-fractions, respectively. Using gel chromatography of pooled plaque extracs from 10 subjects, active fractions were incubated with sucrose. The reaction products were isolated and characterised. The results indicate the presence of at least three groups of sucrose-splitting enzymes: dextransucrase, levansucrase and invertase.
 ...
PMID:Separation of "sucrases" in supernatants of human dental plaque material and characterisation of the reaction products. 105 54

The relative effects in human dental plaque material from the three main extracellular sucrolytic enzymes from bacterial origin, invertase, dextransucrase and levansucrase, have been investigated by means of quantitative determination of products with sucrose as the substrate. Twenty young men having carious lesions and harboring plaque material on the tooth surfaces, were selected. One gram (wet weight) of plaque material was obtained and divided in five samples, 0.2 g each, for different investigations and controls. Twice as much fructan as glucan was found in plaque. Invertase activity was found to dominate sucrolysis within plaque with 99.67% of the total activity.
 ...
PMID:Relative effects of sucrolytic enzymes in human dental plaque. 107 Jan 29

The adjacent sacX and sacY genes are involved in sucrose induction of the Bacillus subtilis sacB gene by an antitermination mechanism. sacB, encoding the exoenzyme levansucrase, is also subject to regulation by the DegS-DegU signalling system. Using sacXY'-lacZ and sacX'-lacZ fusions, we show that the transcription of the sacX and sacY genes is both inducible by sucrose and regulated by DegU. sacX and sacY appear to constitute an operon, since the deletion of the sacX leader region abolished the expression of a sacXY'-lacZ fusion. The degU-dependent promoter was located by deletion analysis and reverse transcriptase mapping 300 nucleotides upstream from the sacX initiator codon. Sucrose induction of the sacX'-lacZ fusion requires either SacY or the homologous SacT antiterminator, which is involved in sucrose induction of the intracellular sucrase gene (sacPA operon). Sequence analysis of the sacX leader region revealed (20 nucleotides downstream from the transcription start site) a putative binding site for these regulators; however, no structure resembling a rho-independent terminator could be found overlapping this site, unlike the situation for sacPA and sacB. Deletion of a segment of the leader region located 100 nucleotides downstream from this site led to constitutive expression of the sacXY'-lacZ and sacX'-lacZ fusions. These results suggest that the mechanism of sucrose induction of sacXY is different from that of sacPA and sacB.
 ...
PMID:Transcription of the Bacillus subtilis sacX and sacY genes, encoding regulators of sucrose metabolism, is both inducible by sucrose and controlled by the DegS-DegU signalling system. 140 Jan 59

Sucrose induces two saccharolytic enzymes in Bacillus subtilis, an intracellular sucrase and an extracellular levansucrase, encoded by sacA and sacB, respectively. It was previously shown that the sacY gene encodes a positive regulator involved in a sucrose-dependent antitermination upstream from the sacB coding sequence. We show here that the sacY product is not absolutely required for sacB induction: a weak but significant induction can be observed in strains harboring a sacY deletion. The sacY-independent induction was altered by mutations located in the sacP and sacT loci but was observed in both sacU+ and sacU32 genetic backgrounds. These results suggest that B. subtilis has two alternative systems allowing sacB induction by sucrose. Both systems also seem to be involved in sacA induction.
 ...
PMID:Induction of saccharolytic enzymes by sucrose in Bacillus subtilis: evidence for two partially interchangeable regulatory pathways. 249 47

The structural gene for the enzyme levanase of Bacillus subtilis (SacC) was cloned in Escherichia coli. The cloned gene was mapped by PBS1 transduction near the sacL locus on the B. subtilis chromosome, between leuA and aroD. Expression of the enzyme was demonstrated both in B. subtilis and in E. coli. The presence of sacC allowed E. coli to grow on sucrose as the sole carbon source. The complete nucleotide sequence of sacC was determined. It includes an open reading frame of 2,031 bp, coding for a protein with calculated molecular weight of 75,866 Da, including a putative signal peptide similar to precursors of secreted proteins found in Bacilli. The apparent molecular weight of purified levanase is 73 kDa. The sacC gene product was characterized in an in vitro system and in a minicell-producing strain of E. coli, confirming the existence of a precursor form of levanase of about 75 kDa. Comparison of the predicted aminoacid sequence of levanase with those of the two other known beta-D-fructofuranosidases of B. subtilis indicated a homology with sucrase, but not with levansucrase. A stronger homology was detected with the N-terminal region of yeast invertase, suggesting the existence of a common ancestor.
 ...
PMID:Characterization of the levanase gene of Bacillus subtilis which shows homology to yeast invertase. 311 19

Pseudomonas syringae pv. phaseolicola, a plant pathogenic pseudomonad, possesses two sucrose-splitting enzymes, a levansucrase and a sucrase. The levansucrase is found both extracellularly and intracellularly, and enzyme synthesis is independent of the carbon source. In addition to levansucrase, cells grown on sucrose contain a sucrase. The two sucrose-splitting enzymes differ in their optimum pH value and optimum temperature as well as in their substrate specificities.
 ...
PMID:[Detection and characterization of a levansucrase and a sucrase in Pseudomonas syringae pv. phaseolicola]. 323 22

A 1.7-kb DNA fragment cloned from Zymomonas mobilis genomic DNA complemented the inability to grow on sucrose of a Suc- mutant of Z. mobilis that was deficient in the production of both extracellular levansucrase and invertase. Analysis of the nucleotide sequence of the fragment found two open reading frames (ORFs), both of which did not correspond to the structural gene for the levansucrase or the invertase. By subcloning each ORF into two different Suc- mutants of Z. mobilis, it has been found that the first ORF (gene zliE) activates the production of the extracellular levansucrase and invertase, and the second ORF (gene zliS) stimulates the secretion of the two enzymes. Gene zliS might contribute to the secretion of proteins having no signal peptide. The expression of zliE and zliS seemed to be under the control of the same promoter.
 ...
PMID:Cloning and characterization of a pair of genes that stimulate the production and secretion of Zymomonas mobilis extracellular levansucrase and invertase. 776 92


1 2 3 4 Next >>