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M Nimtz

Publications and source records attributed to M Nimtz.

At least 55 records · Page 3Linked to original sources
PubMed1998

New saponins from the seeds of Agrostemma githago var. githago.

Two new saponins were isolated from the seeds of Agrostemma githago L. var. githago. On the basis of chemical and spectral evidence their structures were determined to be 3-O-beta-D-xylopyranosyl-(1-->3)-[beta-D-galactopyranosyl-(1-->2)]-beta- D- glucuronopyranosylgypsogenin-28-O-beta-D-xylopyranosyl-(1-->4)- [beta-D-glucopyranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-beta- D-4-O-acetylfucopyranoside and 3-O-beta-D-xylopyranosyl-(1-->3)- [beta-D-galactopyranosyl-(1-->2)]-beta-D-glucuronopyranosyl-gyp sogenin- 28-O-beta-D-xylopyranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)- [beta-D-glucopyranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-beta-D- 4-O-acetylfucopyranoside.

Carbohydrate Conformation↗
PubMed1998

Purification and characterization of a cytotoxic exolipid of Burkholderia pseudomallei.

Burkholderia pseudomallei is the causative agent of melioidosis, an infectious disease, which is increasingly recognized as an important public health problem in various tropical regions. This study describes the identification and characterization of a heat-stable extracellular toxin of B. pseudomallei. After cultivation of B. pseudomallei in liquid media, the heated cell-free supernatant was concentrated by ultrafiltration. The concentrate exhibited a cytotoxic and hemolytic activity which showed remarkable resistance against alkaline and acidic treatments. For further purification, reversed-phase chromatography using a fast-performance liquid chromatography system was performed. After elution with an acetonitrile gradient, a single cytotoxic and hemolytic peak was detected. Structural characterization of the toxin was performed by a combination of mass spectrometric and nuclear magnetic resonance spectroscopic techniques. A highly purified glycolipid, 2-O-alpha-L-rhamnopyranosyl-alpha-L-rhamnopyranosyl-beta-hydroxytetradec anoyl-beta-hydroxytetradecanoate (Rha-Rha-C14-C14), with a molecular mass of 762 Da was identified. The purified exolipid showed a time- and dose-dependent cytotoxic effect on phagocytic (HL60) and nonphagocytic (HeLa) cell lines. In addition, a time- and dose-dependent hemolysis of erythrocytes from various species was observed. The toxin structure makes a detergentlike action most probable. Interestingly, the cytotoxic and hemolytic activities of the glycolipid could be neutralized by albumin. Future studies will concentrate on the role of this exolipid as a virulence factor in the pathogenesis of melioidosis.

Animals↗
PubMed1997

Structure of an acidic exopolysaccharide of Burkholderia pseudomallei.

A recently described water-soluble exopolysaccharide of Burkholderia pseudomallei recognized by the IgG 1 monoclonal antibody 3015 [Steinmetz, I., Rohde, M. & Brenneke, B. (1995) Infect. Immun. 63, 3959-3965] was isolated by repetitive ethanol-precipitation steps and by anion-exchange chromatography. The structure of the polysaccharide was determined by a combination of chemical-derivatization and mass-spectrometric techniques (compositional and methylation analysis, GC/MS, and electrospray-ionization-MS/MS of reduced and permethylated hydrolytic fragments), and two-dimensional 1H-NMR methods (COSY, TOCSY and NOESY) and confirmed by isolation and structural characterization of the depolymerized repeating unit of the polysaccharide. The combined structural data established a linear tetrasaccharide repeating unit consisting of three galactose residues, one bearing a 2-linked O-acetyl group, and a 3-deoxy-D-manno-2-octulosonic acid residue. [-->3)-beta-D-Galp2Ac-(1-->4)-alpha-D-Galp-(1-->3)-beta-D-Galp-(1- ->5)-beta-Kdo-(2-->]n

Burkholderia pseudomallei↗
PubMed1997

Identification of the human Lewis(a) carbohydrate motif in a secretory peroxidase from a plant cell suspension culture (Vaccinium myrtillus L.).

This paper reports for the first time the presence of the human Lewis(a) type determinant in glycoproteins secreted by plant cells. A single glycopeptide was identified in the tryptic hydrolysis of the peroxidase VMPxC1 from Vaccinium myrtillus L. by HPLC/ESI-MS. The oligosaccharide structures were elucidated by ESI-MS-MS and by methylation analysis before and after removal of fucose by mild acid hydrolysis. The major structure determined is of the biantennary plant complex type containing the outer chain motif Lewis(a) [structure in text]. A corresponding fucosyltransferase activity catalyzing the formation of Lewis(a) type structures in vitro was identified in cellular extracts of the suspension cultures.

Amino Acid Sequence↗
PubMed1997

Stable expression of the Golgi form and secretory variants of human fucosyltransferase III from BHK-21 cells. Purification and characterization of an engineered truncated form from the culture medium.

Stable BHK-21 cell lines were constructed expressing the Golgi membrane-bound form and two secretory forms of the human alpha1, 3/4-fucosyltransferase (amino acids 35-361 and 46-361). It was found that 40% of the enzyme activity synthesized by cells transfected with the Golgi form of the fucosyltransferase was constitutively secreted into the medium. The corresponding enzyme detected by Western blot had an apparent molecular mass similar to those of the truncated secretory forms. The secretory variant (amino acids 46-361) was purified by a single affinity-chromatography step on GDP-Fractogel resin with a 20% final recovery. The purified enzyme had a unique NH2 terminus and contained N-linked endo H sensitive carbohydrate chains at its two glycosylation sites. The fucosyltransferase transferred fucose to the O-4 position of GlcNAc in small oligosaccharides, glycolipids, glycopeptides, and glycoproteins containing the type I Galbeta1-3GlcNAc motif. The acceptor oligosaccharide in bovine asialofetuin was identified as the Man-3 branched triantennary isomer with one Galbeta1-3GlcNAc. The type II motif Galbeta1-4GlcNAc in bi-, tri-, or tetraantennary neutral or alpha2-3/alpha2-6 sialylated oligosaccharides with or without N-acetyllactosamine repeats and in native glycoproteins were not modified. The soluble forms of fucosyltransferase III secreted by stably transfected cells may be used for in vitro synthesis of the Lewisa determinant on carbohydrates and glycoproteins, whereas Lewisx and sialyl-Lewisx structures cannot be synthesized.

Animals↗
PubMed1997

The glycosylation of the aspartic proteinases from barley (Hordeum vulgare L.) and cardoon (Cynara cardunculus L.).

Plant aspartic proteinases characterised at the molecular level contain one or more consensus N-glycosylation sites [Runeberg-Roos, P., Tŏrmäkangas, K. & Ostman, A. (1991) Eur. J. Biochem. 202, 1021-1027; Asakura, T., Watanabe, H., Abe, K. & Arai, S. (1995) Eur. J. Biochem, 232, 77-83; Veríssimo, P., Faro, C., Moir, A. J. G., Lin, Y., Tang, J. & Pires, E. (1996) Eur. J. Biochem. 235, 762-768]. We found that the glycosylation sites are occupied for the barley (Hordeum vulgare L.) aspartic proteinase (Asn333) and the cardoon (Cynara cardunculus L.) aspartic proteinase, cardosin A (Asn70 and Asn363). The oligosaccharides from each site were released from peptide pools by enzymatic hydrolysis with peptide-N-glycanase A or by hydrazinolysis and their structures were determined by exoglycosidase sequencing combined with matrix-assisted laser desorption/ionization time of flight mass spectrometry. It was observed that 6% of the oligosaccharides from the first glycosylation site of cardosin A are of the oligomannose type. Modified type glycans with proximal Fuc and without Xyl account for about 82%, 14% and 3% of the total oligosaccharides from the first and the second glycosylation sites of cardosin A and from H. vulgare aspartic proteinase, respectively. Oligosaccharides with Xyl but without proximal Fuc were only detected in the latter proteinase (4%). Glycans with proximal Fuc and Xyl account for 6%, 86% and 92% of total oligosaccharides from the first and second glycosylation sites of cardosin A and from H. vulgare aspartic proteinase, respectively.

Aspartic Acid Endopeptidases↗
PubMed1997

Triterpenoid saponins from Aster bellidiastrum.

Seven triterpenoid saponins were isolated from both the aerial and the underground parts of Aster bellidiastrum. Five of the compounds were common to both parts. The structures were elucidated mainly from their NMR and mass spectral data, and showed significant similarity to the corresponding data for the saponins from plants of the Bellis genus. Two of the saponins are novel compounds with the structures 3-O-beta-D-xylopyranosyl-2 beta,3 beta, 23-trihydroxyolean-12-en-28-oic acid 28-O-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranoside and 3-O-beta-D-glucopyranosyl-2 beta,3 beta,16 alpha, 23-tetrahydroxyolean-12-en-28-oic acid 28-O-alpha-L-arabinofuranosyl(1-->3)-[alpha-L-rhamnopyranosyl(1-->2)]-be ta- D-fucopyranoside.

Carbohydrate Sequence↗
PubMed1997

Molecular characterization of beta-trace protein in human serum and urine: a potential diagnostic marker for renal diseases.

We have isolated beta-trace protein from cerebrospinal fluid, serum, plasma, and urine samples of normal volunteers and sera and hemofiltrate of patients with chronic renal failure. Blood-derived and urinary beta-trace have significantly higher molecular weights than their cerebrospinal fluid counterpart, the amino acid sequences being identical. Oligosaccharide structural analysis revealed these molecular weight differences to be due to different N-glycosylation. beta-Trace from hemofiltrate and urine has larger sugar chains and concurrently significantly higher sialylation than cerebrospinal fluid-beta-trace which bears truncated "brain-type" oligosaccharide chains (published previously). beta-Trace concentrations were about 40 ng/ml for normal sera and plasma. 2000-6000 ng/ml were measured in sera of dialysis patients whereas in normal human cerebrospinal fluid, beta-trace concentration was about 8000 ng/ml. A reduced amount of 900 ng/ml was found in a single case of hydrocephalus cerebri. The sialylated glycoforms of beta-trace detected in the blood are presumably derived from resorbed cerebrospinal fluid protein whereas beta-TP-molecules bearing asialo-oligosaccharides are absent due to their hepatic clearance. The residual, sialylated beta-TP-species are probably eliminated from the blood via the kidney. This physiological clearance mechanism for the sialylated glycoforms is disturbed in hemodialysis patients resulting in about 100-fold elevated serum concentrations. These results let us suggest beta-trace may become a useful novel diagnostic protein in renal diseases.

Amino Acid Sequence↗
PubMed1997

Hypoglycosylation of a brain glycoprotein (beta-trace protein) in CDG syndromes due to phosphomannomutase deficiency and N-acetylglucosaminyl-transferase II deficiency.

Human beta-trace protein is a major intrathecally synthesized polypeptide constituent of human cerebrospinal fluid. We have previously shown that this protein is almost quantitatively modified with biantennary complex-type N-linked oligosaccharides which show "brain-type" glycosylation characteristics (Hoffmann,A. et al., J. Neurochem., 63, pp. 2185-2191, 1994). In the present study human beta-trace protein from the cerebrospinal fluid (CSF) of patients with carbohydrate-deficient glycoprotein syndrome (CDGS) due to phosphomannomutase (PMM) deficiency and N-acetyl-glucosaminyltransferase II (GlcNAc-T II) deficiency as well as from control individuals was studied by Western blot analysis. The protein from pooled CSFs was purified by immunoaffinity chromatography. The protein from the five patients with CDGS PMM deficiency showed three protein bands upon SDS-PAGE analysis corresponding to the di-, mono-, and unglycosylated polypeptide forms. Carbohydrate structural analysis of the enzymatically liberated N-glycans was performed applying mapping by HPAEC-PAD, methylation analysis as well as MALD/TOF-MS. Essentially identical oligosaccharide structures were detected in beta-TP from type I patients and control adult pooled CSF. The beta-trace protein from two patients with GlcNAc-T II deficiency showed a single di-N-glycosylated protein band with a significantly lower molecular weight than the di-glycosylated polypeptide from control patients and the beta-trace protein from pooled adult CSF. Beta-TP from GlcNAc-T II deficiency patients shared only three oligosaccharides out of the 13 observed in beta-TP from controls or patients with PMM deficiency. The major oligosaccharide structures of the glycoprotein from patients with GlcNAc-T II deficiency were found to be monoantennary asialo- or monosialylated lactosamine-type chains with proximal fucose and bisecting GlcNAc.

Adult↗
PubMed1996

Structure of stewartan, the capsular exopolysaccharide from the corn pathogen Erwinia stewartii.

Stewartan, the acidic exopolysaccharide of Erwinia stewartii, was purified from agar grown cells. To facilitate its structural analysis, chemical and enzymatic depolymerizations were carried out using hydrofluoric acid and E. amylovora phage phi-Ea1h, respectively. Structural characterization of the resulting oligosaccharides was performed by a combination of mass spectrometric and one- and two-dimensional (1D/2D) NMR spectroscopic techniques. A branched repeating unit with seven monosaccharide residues, all in their pyranose forms, was found: [Table: see text]

Bacterial Capsules↗
PubMed1996

Structure of amylovoran, the capsular exopolysaccharide from the fire blight pathogen Erwinia amylovora.

The acidic exopolysaccharide (EPS) of Erwinia amylovora, amylovoran, was purified from culture supernatants of bacteria in minimal medium and cleaved chemically either by treatment with trifluoracetic acid or hydrofluoric acid, and enzymatically by digestion with depolymerase from E. amylovora phage phi-Ealh. Structural characterization of the resulting oligosaccharides was performed by a combination of mass spectrometric and NMR [one- and two-dimensional (1D and 2D)] spectroscopic techniques. A branched repeating unit with five monosaccharide residues and various substituents was determined: [sequence: see text] The terminal monosaccharide of the side branch, which bears a 4,6-bound pyruvate residue in the R-configuration, was found to be modified with 2-linked (26%), 3-linked (24%), 2-,3-linked (40%) O-acetyl groups, or these were absent (10%). An additional glucose residue is linked to approximately 10% of the core alpha-galactose of the repeating unit.

Bacterial Capsules↗
PubMed1996

Triterpenoid saponins from Bellium bellidioides. Structures of the minor deacylsaponins.

A new deacylsaponin of polygalacic acid, desacylbellidioside B4, was obtained from the whole plants of Bellium bellidioides L. The structure has been elucidated by a general strategy involving mass spectrometry (ESI-MS, including tandem MS, and GC-MS) and high-field one- and two-dimensional NMR spectroscopy (1H and 13C NMR, COSY-45, HMQC, HMBC) as 3-O-alpha-L-rhamnopyranosyl-2 beta, 3 beta, 16 alpha, 23-tetrahydroxyolean-12-en-28-oic acid 28-O-alpha-L-rhamnopyranosyl(1-->3)-beta-D-xylopyranosyl(1-->4)-alpha-L- rhamnopyranosyl(1-->2)-[alpha-L-arabinofuranosyl(1-->3)-beta-D-fucopyran oside. Moreover, bellissaponin BS2 and besysaponin C12 have also been isolated, demonstrating the close chemical relationship of B. bellidioides to the Bellis genus.

Carbohydrate Conformation↗
PubMed1996

Betacyanins from plants and cell cultures of Phytolacca americana.

Betacyanins from cell cultures of Phytolacca americana were characterized and compared with those of the stems and ripening fruits of the plant. Whereas in fruits prebetanin (betanin 6'-O-sulphate) and its isoform predominate, in the stem and cell cultures feruloylated derivatives occur as the major components. These were rigorously identified by various spectroscopic techniques (DAD-HPLC, NMR, LC-MS and electrospray MS-MS) and carbohydrate analyses as betanidin 5-O-[(5"-O-E-feruloyl)-2'-O-beta-D-apiofuranosyl] -beta-D-glucopyranoside, a new betacyanin of higher plants, and betanidin 5-O-(6'-O-E-feruloyl)-beta-D-glucopyranoside (lampranthin II), together with their isoforms.

Betacyanins↗
PubMed1996

Triterpenoid saponins from Bellis sylvestris. 2. Structures of partially deacylated saponins.

Four saponins have been isolated from the herbal parts of Bellis sylvestris and the same, together with three further compounds, from the underground parts. The structures were elucidated by electrospray ionization mass spectrometry, including tandem mass spectrometry, and by 1D and 2D homonuclear and heteronuclear NMR spectroscopy. Two of the compounds are new saponins with the structures 3-O-beta-D-glucopyranosyl-2 beta, 3 beta, 23-trihydroxyolean-12-en-28-oic acid 28-O-beta-D-glucopyranosyl (1-->3)-[alpha-L-rhamnopyranosyl (1-->2)]-beta-D- glucopyranoside and 3-O-beta-D-glucopyranosyl-2 beta, 3 beta,16 alpha, 23-tetrahydroxyolean-12-en- 28-oic acid 28-O-alpha-L-rhamnopyranosyl (1-->3)-beta-D-xylopyranosyl(1-->4)-alpha-L- rhamnopyranosyl(1-->2)-[(E)-2-butenoic acid (1-->3)]-beta-D-fucopyranoside. Taxonomically these data provide significant evidence of a link between the Bellis genus and Bellium bellidioides.

Carbohydrate Sequence↗
PubMed1996

Triterpenoid saponins from Bellis bernardii.

Nine saponins were isolated from the deacylated saponin mixture obtained from the whole plants of Bellis bernardii. Their structures have been elucidated from NMR and MS data and by chemical derivatization. Three were glycosides of the recently reported bellisonic acid (2 beta, 3 beta,-23-trihydroxy-16-oxoolean-12-en-28-oic acid), with the major compounds being related glycosides of polygalacic acid (2 beta, 3 beta, 16 alpha, 23-tetrahydroxyolean-12-en-28-oic acid). In addition, a saponin of bayogenin (2 beta, 3 beta, 23-trihydroxyolean-12-en-28-oic acid) was obtained and is the first acyl glycoside of this aglycon with a free hydroxyl group at C-3.

Carbohydrate Sequence↗
PubMed1996

Application of MS-MS for the rapid, comparative analysis of saponin mixtures as exemplified by the deacylated and partially deacylated triterpenoid saponins of Bellis annua.

While most species of the Bellis genus are characterized by saponins in concentrations of ca.4% dry weight, Bellis annua only contains ca.0.3% saponins. Hence positive-ion electrospray ionization mass spectrometry, including MS-MS analysis, has been used extensively for the rapid identification of the saponins of B. annua obtained after mild alkaline hydrolysis. The saponin composition is similar to that of other Bellis species and, in addition, glycosides of the rare bellisonic acid, which has recently been found in B. bernardii, have been identified.

Carbohydrate Conformation↗