Wyniki wyszukiwania

1

The in vitro synthesis of diosgenin mono- and diglucoside by enzyme preparations from Solanum melongena leaves

100%

Paczkowski C., Wojciechowski Z. A.

Acta Biochimica Polonica

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1993

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tom 40

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nr 1

2

Evidence for essential histidine and dicarboxylic amino-acid residues in the active site of UDP-glucose: solasodine glucosyltransferase from eggplant leaves

84%

Nawloka P., Kalinowska M., Paczkowski C., Wojciechowski Z. A.

Acta Biochimica Polonica

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2003

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tom 50

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nr 2

Effects of several chemical probes selectively modifying various amino-acid residues on the activity of UDP-glucose : solasodine glucosyltransferase from eggplant leaves was studied. It was shown that diethylpyrocarbonate (DEPC), a specific modifier of histidine residues, was strongly inhibitory. However, in the presence of excessive amounts of the enzyme substrates, i.e. either UDP-glucose or solasodine, the inhibitory effect of DEPC was much weaker indicating that histidine (or histidines) are present in the active site of the enzyme. Our results suggest also that unmodified residues of glutamic (or aspartic) acid, lysine, cysteine, tyrosine and tryptophan are necessary for full activity of the enzyme. Reagents modifying serine and arginine residues have no effect on the enzyme activity.

3

Overexpression of gtfbeta gene fragments from Streptococcus mutans encoding Glu and Cat domains in Escherichia coli

67%

Lipinski D., Zandecka-Dziubak J., Juzwa W., Zeyland J., Mrozikiewicz P. M., Slomski R.

Herba Polonica

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2004

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tom 50

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nr 2

Streptococcus mutans is involved in the initiation and progression of dental caries. Fragments of a gtfB gene from Streptococcus mutans encoding Glu and Cat peptides of approximately 35 and 45 kDa, respectively, were cloned from this organism and sequenced. Recombinant Glu and Cat peptides were overexpressed in Escherichia coli with C-terminal sequence containing additional six histidine residues and enterokinase recognition site. The recombinant peptides were purified from E. coli by metal affinity chromatography. These proteins will be used to prepare efficient vaccine against dental caries.

4

UDP-glucose: solasodine glucosyltransferase from eggplant [Solanum melongena L.] leaves: Partial purification and characterization

67%

Paczkowski C., Kalinowska M., Wojciechowski Z. A.

Acta Biochimica Polonica

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1997

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tom 44

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nr 1

Uridine 5 '-diphosphoglucose-dependent glucosyltransferase which catalyzes the glucosylation of solasodine, i.e. UDP-glucose:solasodine glucosyltransferase, is present in leaves, roots, unripe fruits and unripe seeds of eggplant (Solanum melongenaL.). The glucosylation product is chromatographically identical with authentic solasodine 3β-nmonoglucoside, a putative intermediate in the biosynthesis of solasodine-based glycoalkaloids characteristic of the eggplant. The enzyme was purified about 50-fold from crude cytosol fraction of eggplant leaves by ammonium sulphate precipitation and column chromatography on Q-Sepharose and Sephadex G-100. The native enzyme has a molecular mass of approx. 55 and pH optimum of 8.5. metal ions are not required for its activity but the presence of free -SH groups is essential. Besides solasodine (Km = 0.04 ), the enzyme effectively glucosylates tomatidine, another steroidal alkaloid of the spirosolane type, but it is virtually inactive towards the solanidane-type steroidal alkaloids such as solanidine or demissid- ine. The enzyme is specific for UDP-glucose (Km= 2.1 u) since unlabelled ADP-, GDP-, CDP- or TDP-glucose could not effectively compete with UDP-[14]glucose used as the sugar donor for solasodine glucosylation. Moreover, no synthesis of labelled solasodine galactoside was observed when UDP-l14]glucose was replaced with UDP-[l4]galactose.

Ograniczanie wyników

3 Acta Biochimica Polonica

1 Herba Polonica

3 Paczkowski C.

3 Wojciechowski Z. A.

2 Kalinowska M.

1 Juzwa W.

1 Lipinski D.

1 Mrozikiewicz P. M.

1 Nawloka P.

1 Slomski R.

1 Zandecka-Dziubak J.

1 Zeyland J.

1 2004

1 2003

1 1997

1 1993

The in vitro synthesis of diosgenin mono- and diglucoside by enzyme preparations from Solanum melongena leaves

Evidence for essential histidine and dicarboxylic amino-acid residues in the active site of UDP-glucose: solasodine glucosyltransferase from eggplant leaves

Overexpression of gtfbeta gene fragments from Streptococcus mutans encoding Glu and Cat domains in Escherichia coli

UDP-glucose: solasodine glucosyltransferase from eggplant [Solanum melongena L.] leaves: Partial purification and characterization