Biomedical subjects

T B Ng

Publications and source records attributed to T B Ng.

At least 127 records · Page 7Linked to original sources

PubMed2002

A novel peptide with ribonuclease and translation-inhibitory activities from fruiting bodies of the oyster mushroom Pleurotus ostreatus.

From the fresh fruiting bodies of the oyster mushroom a peptide with a molecular weight of 9 kDa and demonstrating a novel N-terminal sequence GPCYLVAFYESSGRR was isolated. The isolation procedure involved ion exchange chromatography on CM-Sepharose and Mono S. The peptide was adsorbed on both types of chromatographic media. The peptide demonstrated a ribonuclease activity of 650 U/mg toward yeast transfer RNA. It inhibited cell-free translation in a rabbit reticulocyte lysate system with an IC50 of 15 nM.

Amino Acid Sequence↗

PubMed2002

A new peptidic protease inhibitor from Vicia faba seeds exhibits antifungal, HIV-1 reverse transcriptase inhibiting and mitogenic activities.

A new trypsin-chymotrypsin Inhibitor, with an N-terminal sequence showing some differences from the previously reported trypsin-chymotrypsin inhibitor, was isolated from the broad bean Vicia faba. The inhibitor was a peptide with a molecular mass of 13 kDa. It was adsorbed on Affi-gel blue gel and CM-Sepharose. It exerted antifungal activity toward Mycosphaerella arachidicola and Physalospora piricola. In addition, the trypsin-chymotrypsin inhibitor elicited a mitogenic response from mouse splenocytes and inhibited the activity of human immunodeficiency virus-1 reverse transcriptase.

Amino Acid Sequence↗

PubMed2002

Delandin, a chitinase-like protein with antifungal, HIV-1 reverse transcriptase inhibitory and mitogenic activities from the rice bean Delandia umbellata.

An antifungal protein with a chitinase-like N-terminal sequence, designated delandin, was isolated from the rice bean. The protein exhibited a molecular weight of 28 kDa and was adsorbed on both blue Affi-Gel and SP-Toyopearl. It exerted antifungal action toward Mycosphaerella arachidicola, Botrytis cinerea, Fu- sarium oxysporum, Rhizoctonia solani, and Colletotrichum gossypii and inhibited the activity of human immunodeficiency virus 1 reverse transcriptase. The protein inhibited translation in rabbit reticulocyte lysate with a low potency. It elicited a mitogenic response from mouse splenocytes.

Animals↗

PubMed2002

Cicerin and arietin, novel chickpea peptides with different antifungal potencies.

Two antifungal peptides with novel N-terminal sequences, designated cicerin and arietin were isolated from seeds of the chickpea (Cicer arietinum), respectively. Both peptides were adsorbed on Affi-gel blue gel and CM-Sepharose and exhibited a molecular weight of approximately 8.2 and 5.6 kDa, respectively. Arietin was more strongly adsorbed on CM-Sepharose than cicerin and manifested a higher translation-inhibiting activity in a rabbit reticulocyte lysate system and a higher antifungal potency toward Mycosphaerella arachidicola, Fusarium oxysporum and Botrytis cinerea. Both were devoid of mitogenic and anti-HIV-1 reverse transcriptase activities.

Amino Acid Sequence↗

PubMed2002

Ascalin, a new anti-fungal peptide with human immunodeficiency virus type 1 reverse transcriptase-inhibiting activity from shallot bulbs.

An isolation procedure comprising ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on SP-Sepharose and gel filtration on Superdex 75 was used to isolate an anti-fungal peptide from the bulbs of the shallot Allium ascalonicum. The peptide demonstrated a molecular weight of 9.5kDa, and possessed an N-terminal sequence YQCGQGG somewhat similar to chitinases from other Allium species which are however much larger in molecular weight. The peptide designated ascalin manifested a unique specific anti-fungal activity. It inhibited mycelial growth in the fungus Botrytis cinerea but not in the fungi Mycosphaerella arachidicola and Fusarium oxysporum. Ascalin inhibited HIV-1 reverse transcriptase with an IC(50) of 10 microM, much more potently than Allium tuberosum anti-fungal protein and other anti-fungal proteins.

Antifungal Agents↗

PubMed2002

Isolation and characterization of luffacylin, a ribosome inactivating peptide with anti-fungal activity from sponge gourd (Luffa cylindrica) seeds.

A purification scheme involving ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, and ion exchange chromatography on CM-Sepharose and Mono S was employed to isolate a peptide with a molecular weight of 7.8kDa from sponge gourd seeds. The peptide, which was designated luffacylin, exhibited an N-terminal sequence with pronounced resemblance to that of the 6.5kDa arginine-glutamate rich polypeptide previously isolated from sponge gourd seeds. Luffacylin inhibited translation in a rabbit reticulocyte lysate system with an IC(50) of 140pM and reacted positively in the N-glycosidase assay for ribosome inactivating proteins. Luffacylin exerted anti-fungal activity against Mycosphaerella arachidicola and Fusarium oxysporum.

Amino Acid Sequence↗

PubMed2002

A ubiquitin-like peptide from the mushroom Pleurotus sajor-caju exhibits relatively potent translation-inhibitory and ribonuclease activities.

The fruiting bodies of the edible mushroom Pleurotus sajor-caju were extracted with an aqueous buffer and then subjected to affinity chromatography on Affi-gel Blue gel, ion exchange chromatography on DEAE-cellulose and gel filtration on Superdex 75. From the fraction of the extract adsorbed on Affi-gel Blue gel and unadsorbed on DEAE-cellulose, a 9.5 kDa peptide with an N-terminal sequence similar to ubiquitin was isolated with a yield of 0.25 mg/kg mushroom. The peptide inhibited cell-free translation with an IC(50) of 30 nM. It exhibited a ribonuclease activity of 450 U/mg toward yeast transfer RNA. The activities were substantially more potent than those of previously isolated mushroom ubiquitin-like protein and peptide.

Fungal Proteins↗

PubMed2002

Purification and characterization of moschins, arginine-glutamate-rich proteins with translation-inhibiting activity from brown pumpkin (Cucurbita moschata) seeds.

From fresh brown pumpkin seeds, two proteins with a molecular mass of 12kDa and an N-terminal sequence rich in arginine and glutamate residues were obtained. The protein designated alpha-moschin closely resembled the fruitfly programmed-cell death gene product and the protein designated beta-moschin demonstrated striking similarity to prepro 2S albumin in N-terminal sequence. alpha- and beta-moschins inhibited translation in the rabbit reticulocyte lysate system with an IC(50) of 17 microM and 300nM, respectively.

Amino Acid Sequence↗

PubMed2002

Hispin, a novel ribosome inactivating protein with antifungal activity from hairy melon seeds.

A ribosome inactivating protein demonstrating a molecular mass of 21 kDa and a novel N-terminal sequence was isolated from seeds of the hairy melon. The purification procedure involved affinity chromatography on Affi-gel blue gel and ion exchange chromatography on CM-Sepharose and Mono S. The protein designated hispin inhibited translation in the cell-free rabbit reticulocyte lysate system with an IC50 of 165 pM and exhibited N-glycosidase activity. Antifungal activity was also observed.

Amino Acid Sequence↗

PubMed2002

Purification and characterization of a rhamnose-binding lectin with immunoenhancing activity from grass carp (Ctenopharyngodon idellus) ovaries.

A rhamnose-specific lectin was isolated from ovaries of the grass carp (Ctenopharyngodon idellus). The grass carp lectin possesses a molecular mass of 205 kDa. It is composed of six subunits each with a molecular mass of 35 kDa. The N-terminal amino acid sequence of the grass carp shows similarity to those of other fish species with 26-35% amino acid identity. It is mitogenic toward murine splenocytes and peritoneal exudate cells.

Amino Acid Sequence↗

PubMed2002

Production of a polyclonal antibody against recombinant goldfish prolactin and demonstration of its usefulness in a non-competitive antigen-capture ELISA.

The cDNA encoding the goldfish (Carassius auratus) prolactin was expressed in Escherichia coli using the pRSETA expression vector. The recombinant goldfish prolactin (gfPRL) produced was a fusion protein containing a hexahistidyl sequence, which facilitated its purification on a Ni(2+) column. The fusion protein was overexpressed in the bacteria as inclusion bodies and was successfully purified under denaturing conditions by one-step affinity chromatography. Repeated immunization of rabbits against the purified recombinant gfPRL allowed the production of a high-titer polyclonal antiserum. The IgG fraction of the antiserum was isolated on an immobilized Protein A-agarose column. The antibody recognized recombinant gfPRL, but not recombinant goldfish growth hormone (gfGH) or goldfish somatolactin (gfSL) on Western analyses. The purified antibody was able to recognize gfPRL, but not gfGH or gfSL, in a non-competitive antigen-capture ELISA. The assay was applied in monitoring the purification of native PRL from goldfish pituitaries.

Animals↗

PubMed2002

Solenin, a novel protein with translation-inhibiting activity from the traditional Chinese medicinal fish, the sea dragon Solenognathus hardwickii.

A single-chained protein designated solenin was isolated from Solenognathus hardwickii, a fish used as traditional Chinese medicinal material. Solenin was capable of inhibiting translation in a cell-free rabbit reticulocyte lysate system with an IC(50) of 2 microM and expressing a ribonuclease activity of 0.8U/mg toward yeast transfer RNA, but it lacked N-glycosidase activity characteristic of ribosome inactivating proteins Solenin exhibited a molecular weight of 18kDa and possessed an N-terminal sequence AHDAEVNEVKAQVAA. The protein was adsorbed on three types of chromatographic media: Affi-gel blue gel, CM-Sepharose and Mono S. It was devoid of antifungal and lectin activities.

Amino Acid Sequence↗

PubMed2002

Demonstration of antifungal and anti-human immunodeficiency virus reverse transcriptase activities of 6-methoxy-2-benzoxazolinone and antibacterial activity of the pineal indole 5-methoxyindole-3-acetic acid.

6-methoxy-2-benzoxazolinone (6-MBOA), a naturally occurring progonadal compound present in grasses with structural resemblance to melatonin, was tested for antifungal activity against Fusarium oxysporum, Rhizoctonia solani and Coprinus comatus. A variety of pineal products was also examined for the sake of comparison, including 5-methoxytryptamine, melatonin, 5-methoxytryptophol, 5-hydroxytryptamine, 5-methoxyindole-3-acetic acid and 5-hydroxytryptophol. The assay for antifungal activity was carried out in Petri plates containing potato dextrose agar. It was found that 6-MBOA most potently inhibited the growth of C. comatus, R. solani and F. oxysporum. When 6-MBOA and pineal indoles were tested for antibacterial activity against the bacterium Agrobacterium tumefaciens, 5-methoxyindole-3-acetic acid was found to be the most potent. 6-MBOA most potently inhibited human immunodeficiency virus-1 reverse transcriptase.

Agrobacterium tumefaciens↗

PubMed2002

Isolation of a novel legumin-like lectin with potent hemagglutinating activity from seeds of the Chinese chestnut Castanea mollisima.

A novel mannose- and glucose-specific lectin with high hemagglutinating activity was isolated from seeds of the Chinese chestnut Castanea mollisima. The lectin possessed a molecular mass of 140 kDa and was made up of two subunits, one with a molecular mass of 31 kDa and another with a molecular mass of 32 kDa. They exhibited substantial homology in N-terminal sequence to the storage protein legumin. The lectin was unstable in the presence of acid and alkali and at temperatures above 50 degrees C, but it was unaffected by various salts. The lectin was purified with a procedure involving ion exchange chromatography on CM-Sepharose, Q-Sepharose and Resource Q and gel filtration on Superose 12.

Animals↗

PubMed2002

Purification and characterization of charantin, a napin-like ribosome-inactivating peptide from bitter gourd (Momordica charantia) seeds.

A peptide designated charantin, with a molecular mass of 9.7 kDa, was isolated from bitter gourd seeds. The procedure comprised affinity chromatography on Affi-gel blue gel, ion-exchange chromatography on Mono S and gel filtration on Superdex 75. The N-terminal sequence of charantin exhibited marked similarity to that of the 7.8-kDa napin-like peptide previously isolated from bitter gourd seeds. Charantin inhibited cell-free translation in a rabbit reticulocyte lysate system with an IC50 of 400 nm, a potency lower than that of the previously reported small ribosome-inactivating protein gamma-momorcharin (IC50 = 55 nm) which also exhibited an abundance of arginine and glutamate/glutamine residues. Charantin reacted positively in the N-glycosidase assay, yielding a band similar to that formed by the small ribosome-inactivating proteins gamma-momorcharin and luffin S.

2S Albumins, Plant↗

PubMed2002

A new antifungal peptide from rice beans.

A peptide, possessing a molecular mass of 5 kDa and demonstrating remarkable sequence homology to the cowpea 10 kDa protein precursor and garden pea disease resistance response protein, was isolated from rice bean seeds. The peptide was adsorbed on CM-Sepharose and Affi-gel blue gel. It inhibited mycelial growth in the fungi Botrytis cinerea, Fusarium oxysporum, Rhizoctonia solani and Mycosphaerella arachidicola. It stimulated incorporation of methyl [3H] thymidine into mouse splenocytes, inhibited the activity of human immunodeficiency virus type 1 reverse transcriptase and suppressed translation by rabbit reticulocyte lysate.

Amino Acid Sequence↗

PubMed2002

Pananotin, a potent antifungal protein from roots of the traditional chinese medicinal herb Panax notoginseng.

The roots of the sanchi ginseng, Panax notoginseng, were extracted with an aqueous buffer. The extract was chromatographed on a CM-cellulose column to remove extraneous unadsorbed proteins. The adsorbed fraction was dialyzed and chromatographed on Affi-gel blue gel. The adsorbed fraction was again collected, dialyzed and applied on a column of Mono S. The second peak was dialyzed and chromatographed on an FPLC-gel filtration Superdex 75 column. An antifungal protein with an N-terminal sequence similar to those of chitinases was isolated from the first peak which had a molecular mass of 35 kDa. The sequence was distinctive in that the third and ninth highly conserved N-terminal residues (C and G) were replaced by H and M, respectively. The protein inhibited mycelial growth in Coprinus comatus, Physalospora piricola, Botrytis cinerea, and Fusarium oxysporum with an IC 50 of 100 nM, 1 microM, 630 nM and 560 nM, respectively. It inhibited cell-free translation with an IC 50 of 630 nM. Its antifungal and translation-inhibitory activities were more potent than those of previously reported antifungal proteins. It inhibited human immunodeficiency virus-1 reverse transcriptase by 35.8 % at 12.6 microM and 24.7 % at 1.26 microM.

Amino Acid Sequence↗

PubMed2002

Gene expression of immunomodulatory cytokines induced by Narcissus tazetta lectin in the mouse.

The immunomodulation of Narcissus tazetta lectin (NTL) on the induction of gene expression of cytokines in the mouse was studied using specific cytokine primers, total RNA isolated from mouse splenocytes and macrophages, and reverse transcription-polymerase chain reaction (RT-PCR). For comparison, a fungal antimitogenic lectin from Agaricus bisporus (ABL) was used to test and compare the acute (kinetic) induction of cytokine gene expression. NTL was able to induce the expression of IL-1beta, TNF-alpha, and immunoreactive nitric oxide synthase (NOS) in both splenocytes and macrophages in vivo after 10-day consecutive peritoneal injections of 5 mg NTL x kg(-1) x day(-1) in the mouse. Nevertheless, the expression levels of IFN-gamma and TGF-beta were markedly increased in macrophages, and the levels of IL-2 and IL-4 were up-regulated only in splenocytes. From the kinetic pattern of cytokine induction and gene expression, ABL appeared to induce the up-regulation of IL-1beta and TNF-alpha in splenocytes up to 24 h, whereas NTL showed a more sustained effect on the expression of these cytokines in macrophages. While NTL manifested TGF-beta expression at the onset of 12 and 24 h in macrophages and splenocytes, respectively, ABL induced TGF-beta in neither splenocytes nor macrophages. After injection of NTL, stem-cell factor was clearly down-regulated in macrophages at 24 and 48 h but up-regulated in splenocytes at the end of 24 h. The immunopotentiating effect of NTL is quite similar to that of LZ-8, a fungal immunomodulatory lectin isolated from the Chinese premier medicinal mushroom Ganoderma lucidium. However, the mechanism of immunomodulation of NTL still awaits to be elucidated.

Adjuvants, Immunologic↗