Biomedical subjects

T B Ng

Publications and source records attributed to T B Ng.

At least 19 recordsLinked to original sources

PubMed2007

An alkaline protease from fresh fruiting bodies of the edible mushroom Pleurotus citrinopileatus.

A protease was purified from fresh fruiting bodies of the edible mushroom Pleurotus citrinopileatus. The isolation procedure included ion exchange chromatography on DEAE-cellulose, CM-cellulose, and Q-Sepharose and fast protein liquid chromatography-gel filtration on Superdex 75. The protease was unadsorbed on DEAE-cellulose and Q-Sepharose, but adsorbed on CM-cellulose. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the protease demonstrated a single band with a molecular mass of 28 kDa. The protease showed an optimal pH at 10 and an optimal temperature at 50 degrees C. The activity of the protease was not affected by EDTA, indicating that it is not a metalloprotease. The protease exhibited a higher activity in the presence of K(+) and Li(+), but its activity was potently inhibited by Al(3+), Cu(2+), and Hg(2+) ions. It manifested a K (m) of 3.44 mg/ml and a V (max) of 0.139 mg ml(-1) min(-1). It was devoid of ribonuclease and antifungal activities.

Amino Acid Sequence↗

PubMed2006

Isolation and characterization of an antifungal peptide with antiproliferative activity from seeds of Phaseolus vulgaris cv. 'Spotted Bean'.

A 7.3-kDa antifungal peptide with an N-terminal sequence exhibiting remarkable homology to defensins from other leguminous plants was isolated from Phaseolus vulgaris cv. 'Spotted Bean'. The isolation procedure involved ion exchange chromatography on O-diethylaminoethyl (DEAE) cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on SP-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. The peptide was unadsorbed on DEAE-cellulose and adsorbed on Affi-gel blue gel and SP-Sepharose. It exerted an antifungal action on Fusarium oxysporum and Mycosphaerella arachidicola. It inhibited mycelial growth in F. oxysporum with an IC(50) value of 1.8 microM. It suppressed [methyl-(3)H]-thymidine incorporation by leukemia L1210 cells and MBL2 cells with an IC(50) value of 4.0 and 9.0 microM, respectively. There was no effect on HIV-1 reverse transcriptase activity when the peptide was tested up to 0.1 mM.

Antifungal Agents↗

PubMed2006

Bacisubin, an antifungal protein with ribonuclease and hemagglutinating activities from Bacillus subtilis strain B-916.

An antifungal protein, with a molecular mass of 41.9 kDa, and designated as bacisubin, was isolated from a culture of Bacillus subtilis strain B-916. The isolation procedure consisted of ion exchange chromatography on DEAE-Sepharose Fast Flow, and fast protein liquid chromatography on Phenyl Sepharose 6 Fast Flow and hydroxyapatite columns. The protein was adsorbed on all three chromatographic media. Bacisubin exhibited inhibitory activity on mycelial growth in Magnaporthe grisease, Sclerotinia sclerotiorum, Rhizoctonia solani, Alternaria oleracea, A. brassicae and Botrytis cinerea. The IC50 values of its antifungal activity toward the last four fungal species were 4.01 microM, 0.087 microM, 0.055 microM and 2.74 microM, respectively. Bacisubin demonstrated neither protease activity, nor protease inhibitory activity. However, it manifested ribonuclease and hemagglutinating activities.

Amino Acid Sequence↗

PubMed2006

An antifungal peptide from red lentil seeds.

An antifungal peptide, with a molecular mass of 11 kDa, was isolated from dry seeds of the red lentil (Lens culinaris) using a procedure that involved four chromatographic steps. The antifungal peptide was unadsorbed on DEAE-cellulose, and adsorbed on Affi-gel blue gel and S-Sepharose. The final chromatographic step involved gel filtration by fast protein liquid chromatography on Superdex 75. The antifungal peptide inhibited mycelial growth in Mycosphaerella arachidicola with an IC50 of 36 microM. It also exhibited antifungal activity against Fusarium oxysporum, but there was no inhibitory activity toward tumor cell lines and human immunodeficiency virus type 1 reverse transcriptase (RT).

Amino Acid Sequence↗

PubMed2006

A peptide with HIV-1 reverse transcriptase inhibitory activity from the medicinal mushroom Russula paludosa.

Hot water extracts of 16 species of mushrooms, including both edible and medicinal mushrooms, were screened for human immunodeficiency virus (HIV)-1 reverse transcriptase (RT) inhibitory activity. Extracts of Lactarius camphoratus, Trametes suaveolens, Sparassis crispa, Pleurotus sajor-caju, Pleurotus pulmonarius, and Russula paludosa elicited over 50% inhibition when tested at the concentration of 1 mg/ml. The extract of R. paludosa demonstrated the highest inhibitory activity on HIV-1 RT (97.6%). Fraction SU2, purified from R. paludosa extract by anion exchange chromatography on DEAE-cellulose and gel filtration on Superdex 75, exhibited potent inhibitory activity on HIV-1 RT. At the concentrations of 1 mg/ml, 0.2 mg/ml, and 0.04 mg/ml, the inhibition ratios were 99.2%, 89.3%, and 41.8%, respectively, giving an IC50 of 11 microM. The molecular mass of SU2 was 4.5 kDa and its N-terminal amino acid sequence was determined to be KREHGQHCEF. The peptide was devoid of hemagglutinating, ribonuclease, antifungal, protease, protease inhibitory, and laccase activities.

Agaricales↗

PubMed2006

A mannose-specific tetrameric lectin with mitogenic and antibacterial activities from the ovary of a teleost, the cobia (Rachycentron canadum).

A tetrameric lectin, with hemagglutinating activity toward rabbit erythrocytes and with specificity toward D-mannosamine and D(+)-mannose, was isolated from the ovaries of a teleost, the cobia Rachycentron canadum. The isolation protocol comprised ion exchange chromatography on CM-cellulose and Q-Sepharose, ion exchange chromatography by fast protein liquid chromatography (FPLC) on Mono Q, and finally gel filtration by FPLC on Superose 12. The lectin was adsorbed on all ion exchangers used. It exhibited a molecular mass of 180 kDa in gel filtration on Superose 12 and a single 45-kDa band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that it is a tetrameric protein. The hemagglutinating activity of the lectin was stable up to 40 degrees C and between pH 4 and pH 10. All hemagglutinating activity disappeared at 60 degrees C and at pH 1 and pH 13. The hemagglutinating activity was doubled in the presence of 0.1 microM FeCl3. The lectin exerted antibacterial activity against Escherichia coli with 50% inhibition at 250 microg. There was no antifungal activity toward Coprinus comatus, Fusarium oxysporum, Mycosphaerella arachidicola, and Rhizoctonia solani at a dose of 300 microg. The lectin exhibited maximal mitogenic response from mouse splenocytes at a concentration of 14 microM.

Animals↗

PubMed2006

A lectin with antifungal and mitogenic activities from red cluster pepper (Capsicum frutescens) seeds.

A monomeric mannose/glucose-binding lectin, with a molecular mass of 29.5 kDa and an N-terminal sequence GQRELKL showing resemblance to that of the lectin-like oxidized low-density lipoprotein receptor from the rabbit, has been isolated from the seeds of red cluster pepper Capsium frutescens L. var. fasciculatum. The protocol involved anion exchange chromatography on diethylamino ethanol-cellulose and Q-Sepharose and fast protein liquid chromatography on Mono Q. Its hemagglutinating activity toward rabbit erythrocytes was inhibited by D: -mannose and glucose, specifically. The activity was stable from 0 to 40 degrees C, reached a maximum at pH 7 and 8, and was potentiated by Ca2+ and Mn2+ ions. The lectin showed strong mitogenic activity toward spleen cells isolated from BALB/c mice. The mitogenic activity, which reached a peak at a lectin concentration of 0.27 microM, was inhibited specifically by D(+)-mannose. The lectin was capable of inhibiting the germination of Aspergillus flavus and Fusarium moniliforme spores and hyphal growth in the two fungi.

Animals↗

PubMed2006

A hemagglutinin with mitogenic activity from dark red kidney beans.

A 67-kDa hemagglutinin composed of two identical subunits was purified from Phaseolus vulgaris cv. 'Dark Red Kidney Bean'. It was unadsorbed on DEAE-cellulose but adsorbed on Affi-gel blue gel. The hemagglutinin was highly purified after the two aforementioned chromatographic steps as revealed by a single peak in gel filtration on Superdex 75 and a single band in SDS-PAGE. The hemagglutinating activity was stable between 25 degrees C and 70 degrees C, and between pH 4 and pH 11, and in the presence of a variety of divalent metal chlorides at 500 mM concentration. The activity was reduced by 50% at 80 degrees C, and also when the pH was lowered to 3 or elevated to 12. The activity was reduced by 75% in the presence of 250 mM KCl or NaCl. A variety of sugars tested failed to inhibit the hemagglutinating activity of the hemagglutinin. Although the hemagglutinin exhibited mitogenic activity toward murine splenocytes, it had no effect on the activity of HIV-1 reverse transcriptase or mycelial growth in the fungi Botrytis cinerea, Fusarium oxysporum and Mycosphaerella arachidicola. It exerted an antiproliferative activity on leukemia L1210 cells.

Animals↗

PubMed2006

First report of a xylose-specific lectin with potent hemagglutinating, antiproliferative and anti-mitogenic activities from a wild ascomycete mushroom.

From fresh fruiting bodies of the wild ascomycete mushroom (Xylaria hypoxylon) a lectin with N-terminal sequence resemblance to a part of Aspergillus oryzae genome and only slight similarity to fungal immunomodulatory protein from the mushroom Flammulina velutipes was isolated. The protocol comprised extraction with water, precipitation from the aqueous extract using 80% saturated (NH(4))(2)SO(4), ion exchange chromatography on DEAE-cellulose and CM-cellulose, and then gel filtration by fast protein liquid chromatography on Superdex 75. Lectin activity was adsorbed on DEAE-cellulose and unadsorbed on CM-cellulose. The lectin appeared as a single band with a molecular mass of 14.4 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a single 28.8-kDa peak in gel filtration on Superdex 75. The lectin exhibited highly potent antiproliferative activity toward tumor cell lines, and exerted a potent anti-mitogenic action on mouse splenocytes. The hemagglutinating activity of the lectin was inhibited by inulin and xylose. It was stable up to 35 degrees C. At 40 degrees C its hemagglutinating activity was reduced by 50%, and it dwindled to 12.5% of the original activity at 50 degrees C. The hemagglutinating activity was also sensitive to NaOH and HCl solutions. The hemagglutinating activity was unaffected by CaCl(2) and ZnCl(2), and was potentiated substantially in the presence of AlCl(3) and FeCl(3). The distinctive features of this lectin comprise a unique sugar specificity, and highly potent hemagglutinating, antiproliferative and anti-mitogenic activities. X. hypoxylon lectin differs in molecular mass, N-terminal sequence and sugar specificity from previously reported ascomycete mushroom lectins.

Amino Acid Sequence↗

PubMed2006

An antifungal peptide from baby lima bean.

A 6-kDa antifungal peptide with inhibitory activity on mycelial growth in Fusarium oxysporum, Mycosphaerella arachidicola, and Physalospora piricola was isolated from baby lima beans. The peptide suppressed growth in M. arachidicola with an IC(50) of 0.87 muM and inhibited activity of HIV-1 reverse transcriptase with an IC(50) of 4 muM. The peptide exhibited an N-terminal amino acid sequence similar to those of leguminous defensins. The isolation procedure comprised ion exchange chromatography on diethylaminoethyl (DEAE)-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on carboxymethyl (CM)-cellulose, and gel filtration by fast protein liquid chromatography on Superdex 75. The peptide was unadsorbed on DEAE-cellulose and Affi-gel blue gel but was adsorbed on CM-cellulose.

Amino Acid Sequence↗

PubMed2006

A hemolysin from the mushroom Pleurotus eryngii.

A monomeric 17-kDa hemolysin designated as eryngeolysin was isolated from fresh fruiting bodies of the mushroom Pleurotus eryngii, using a protocol that involved gel filtration on Superdex 75, ion exchange chromatography on Mono Q and gel filtration on Superdex 75. Its N-terminal sequence demonstrated striking homology to that of its counterparts ostreolysin from the oyster mushroom Pleurotus ostreatus and aegerolysin from the mushroom Agrocybe cylindracea. Its hemolytic activity was unaffected over the pH range 4.0-12.0, but no activity was observed at pH 13 and at and below pH 2. The hemolysin was stable between 0 and 30 degrees C. At 40 degrees C, only residual activity was detectable. At and above 50 degrees C, activity was indiscernible. Eryngeolysin exhibited cytotoxicity toward leukemia (L1210) cells but not toward fungi. The hemolysin was inactivated by treatment with trypsin. It exhibited antibacterial activity against Bacillus sp. but not against other species. It inhibited basal as well as ConA-stimulated mitogenic response of murine splenocytes. N-Glycolyneuraminic acid was the only sugar capable of inhibiting the hemolytic activity. Eryngeolysin-induced hemolysis was osmotically protected by polyethylene glycol (PEG) 10000 with a mean hydrated diameter dose to 9.3 nm. However, no protection was offered by PEG 10000 to the anti-mitogenic and antiproliferative activities of eryngeolysin. The susceptibility of erythrocytes from different classes of vertebrates to eryngeolysin was mammalian > avian > reptilian > piscine.

Cell Proliferation↗

PubMed2006

A lectin with some unique characteristics from the samta tomato.

A lectin, with a molecular mass of 79 kDa, and with specificity toward rhamnose and O-nitrophenyl-beta-D-galactopyranoside, was isolated from samta tomato fruits. The procedure entailed ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose and gel filtration by fast protein liquid chromatography on Superdex 75. The lectin was unadsorbed on DEAE-cellulose but adsorbed on Affi-gel blue gel and CM-cellulose. The lectin was stable up to 70 degrees C. The lectin activity was potentiated by NaOH solutions (25-100 mM), but was reduced by 50 and 100 mM HCl solutions. The activity of the lectin was reduced in the presence of CaCl(2), MgCl(2) and ZnCl(2), but was potentiated by 5 and 10 mM AlCl(3) solutions. The lectin stimulated the mitogenic response in mouse splenocytes and inhibited human immunodeficiency virus-1 reverse transcriptase with an IC(50) of 6.2 microM.

Animals↗

PubMed2006

Isolation and characterization of a novel lectin from the mushroom Armillaria luteo-virens.

From the dried fruiting bodies of the mushroom Armillaria luteo-virens, a dimeric lectin with a molecular mass of 29.4 kDa has been isolated. The purification procedure involved (NH(4))(2)SO(4) precipitation, ion exchange chromatography on DEAE-cellulose, CM-cellulose, and Q-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. The hemagglutinating activity of the lectin could not be inhibited by simple sugars but was inhibited by the polysaccharide inulin. The activity was stable up to 70 degrees C but was acid- and alkali-labile. Salts including FeCl(3), AlCl(3), and ZnCl(2) inhibited the activity whereas MgCl(2), MnCl(2), and CaCl(2) did not. The lectin stimulated mitogenic response of mouse splenocytes with the maximal response achieved by 1microM lectin. Proliferation of tumor cells including MBL2 cells, HeLa cells, and L1210 cells was inhibited by the lectin with an IC(50) of 2.5, 5, and 10 microM, respectively. However, proliferation of HepG2 cells was not affected. The novel aspects of the isolated lectin include a novel N-terminal sequence, fair thermostability, acid stability, and alkali stability, together with potent mitogenic activity toward spleen cells and antiproliferative activity toward tumor cells.

Agaricales↗

PubMed2006

A laccase from the medicinal mushroom Ganoderma lucidum.

A protein demonstrating laccase activity and potent inhibitory activity towards human immunodeficiency virus (HIV)-1 reverse transcriptase (IC50 1.2 microM) was isolated from fresh fruiting bodies of the medicinal mushroom Ganoderma lucidum. The laccase had a novel N-terminal sequence and a molecular mass of 75 kDa, which is higher than the range (55-56 kDa) reported for most other mushroom laccases. It was isolated by sequential chromatography on DEAE-cellulose and Affi-gel blue gel and adsorption on Con A-Sepharose. Unlike some of the previously isolated laccases, it was adsorbed only on Con A-Sepharose. The enzyme required a pH of 3-5 and a temperature of 70 degrees C to exhibit maximal activity. Minimal activity was detected at pH 6 and 7. Activity was undetectable at pH 8 and 9 and after exposure to 100 degrees C for 10 min.

Chromatography↗

PubMed2006

Hypoglycemic activity of the fungi Cordyceps militaris, Cordyceps sinensis, Tricholoma mongolicum, and Omphalia lapidescens in streptozotocin-induced diabetic rats.

Crude extracts were prepared from fruiting bodies and mycelia of the medicinal fungus Cordyceps militaris, and a polysaccharide-enriched fraction was obtained after extraction with hot water and ethanol precipitation. Polysaccharide-enriched fractions were similarly prepared from Cordyceps sinensis, Omphalia lapidescens, and Tricholoma mongolicum. The various aforementioned preparations were orally administered into different groups of adult rats 24 h before an intraperitoneal injection of streptozotocin (40 mg/kg body weight), and subsequently daily for another 4 days. The dosage used was 10 mg/kg body weight for polysaccharide-enriched preparations and 100 mg/kg body weight for crude extracts. Control rats received distilled water instead of crude extract or polysaccharide-enriched preparation. It was found in the control rats that plasma glucose level rose from about 90 mg/dl before streptozotocin injection to levels that were maintained at about 300 mg/dl postinjection. All preparations produced hypoglycemic effects. C. militaris polysaccharide-enriched fraction displayed a more prominent effect than that of C. sinensis polysaccharide-enriched fraction which in turn was more potent than that of O. lapidescens and T. mongolicum polysaccharide-enriched fractions. The hypoglycemic effect of C. militaris polysaccharide-enriched fraction was dose-dependent.

Administration, Oral↗

PubMed2006

An antifungal protein from the pea Pisum sativum var. arvense Poir.

An antifungal protein with a molecular mass of 11 kDa and a lysine-rich N-terminal sequence was isolated from the seeds of the pea Pisum sativum var. arvense Poir. The antifungal protein was unadsorbed on DEAE-cellulose but adsorbed on Affi-gel blue gel and CM-cellulose. It exerted antifungal activity against Physalospora piricola with an IC50 of 0.62 microM, and also antifungal activity against Fusarium oxysporum and Mycosphaerella arachidicola. It inhibited human immunodeficiency virus type 1 reverse transcriptase with an IC50 of 4.7 microM.

Amino Acids↗

PubMed2006

Purification and characterization of a galactose-specific lectin with mitogenic activity from pinto beans.

A galactose-specific dimeric lectin from pinto beans was purified using a procedure that involved affinity chromatography on Affi-gel blue gel, anion exchange chromatography on Q-Sepharose, fast protein liquid chromatography (FPLC)-ion exchange chromatography on Mono S, and FPLC-gel filtration on Superdex 200. The molecular mass of this homodimeric lectin was 62 kDa and that of each of its subunits was 31 kDa. The hemagglutinating activity of pinto bean lectin was stable within the pH range of 3-12 and the temperature range of 0-70 degrees C. By using the [3H-methyl]-thymidine incorporation assay, it was shown that the lectin had the ability to evoke a mitogenic response from murine splenocytes but it did not inhibit proliferation of L1210 leukemia cells. The pinto bean lectin inhibited HIV-1 reverse transcriptase with an IC50 of 3 microM.

Animals↗

PubMed2006

A ribonuclease from the wild mushroom Boletus griseus.

A ribonuclease (RNase) with a molecular mass of 29 kDa and cospecific for poly A and poly U was isolated from fruiting bodies of the mushroom Boletus griseus. Its N-terminal sequence exhibited some similarity to those of RNases from the mushrooms Irpex lacteus and Lentinus edodes. The RNase was adsorbed on diethylaminoethyl-cellulose, Q-Sepharose, and Affi-gel blue gel and was unadsorbed on CM-cellulose. The enzyme exhibited a temperature optimum between 60 and 70 degrees C and a pH optimum at 3.5.

Agaricales↗