Biomedical subjects

T B Ng

Publications and source records attributed to T B Ng.

At least 145 records · Page 8Linked to original sources

PubMed2001

Antiproliferative and antimitogenic activities in a peptide from puffball mushroom Calvatia caelata.

A peptide with a molecular weight of 8 kDa and an N-terminal sequence closely resembling that of ubiquitin was isolated from fruiting bodies of the mosaic puffball mushroom Calvatia caelata. The peptide was purified using a protocol that involved ion-exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, and ion-exchange chromatography on Mono S. The peptide inhibited translation in the cell-free rabbit reticulocyte lysate system and exhibited N-glycosidase activity. It potently inhibited proliferation of spleen cells with an IC(50) of about 100 nM as indicated by the suppression of [methyl-(3)H]thymidine uptake. The viability of breast cancer cells was reduced to half at a ubiquitin concentration of about 100 nM.

Agaricales↗

PubMed2001

Pleureryn, a novel protease from fresh fruiting bodies of the edible mushroom Pleurotus eryngii.

A protease designated pleureryn, with an N-terminal sequence dissimilar from previously reported mushroom metalloendopeptidases and showing only limited resemblance to aspartic proteinases, albeit considerable homology to DNA replication licensing factor, was isolated from fresh fruiting bodies of the edible mushroom Pleurotus eryngii. The purification protocol entailed ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel Blue gel, ion exchange chromatography on CM-Sepharose, and FPLC-gel filtration on Superdex 75. The protease was unadsorbed on DEAE-cellulose but adsorbed on Affi-gel Blue gel and CM-Sepharose. It demonstrated a single band with a molecular weight of 11.5 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Pleureryn demonstrated a protease activity of 9364 U/mg toward casein. It exhibited a pH optimum of 5.0 and a temperature optimum of 45 degrees C, with substantial activity remaining at high temperatures and pH 4 and 12. The activity of the protease was adversely affected by pepstatin A, indicating that it is an aspartic protease. PMSF, trypsin inhibitor, and EDTA exerted no striking effect, suggesting that it is neither a serine protease nor a metalloprotease. It inhibited translation in a rabbit reticulocyte lysate system with an IC(50) of 20 nM. Pleureryn also exhibited some inhibitory activity against HIV-1 reverse transcriptase, reminiscent of a suppressive action of HIV-1 protease on its homologous reverse transcriptase but was devoid of ribonuclease, deoxyribonuclease, and antifungal activities.

Amino Acid Sequence↗

PubMed2001

Purification of allivin, a novel antifungal protein from bulbs of the round-cloved garlic.

A novel antifungal protein, designated allivin, was isolated from bulbs of the round-cloved garlic Allium sativum var. round clove with a procedure involving ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-Sepharose and FPLC-gel filtration on Superdex 75. Allivin possessed an N-terminal sequence demonstrating very little similarity to sequences of Allium sativum chitinases and ribosome inactivating proteins. Allivin exhibited a molecular weight of 13 kDa in gel filtration and SDS-polyacrylamide gel electrophoresis. It displayed antifungal activity against Botrytis cinerea, Mycosphaerella arachidicola and Physalospora piricola. It inhibited translation in a cell-free rabbit reticulocyte system with an IC50 of 1.6 microM.

Amino Acid Sequence↗

PubMed2001

Isolation of a novel deoxyribonuclease with antifungal activity from Asparagus officinalis seeds.

A deoxyribonuclease distinct from the previously isolated asparagus ribosome-inactivating proteins, possessing a molecular weight of 30 kDa and requiring a pH of 7.5 for optimum hydrolytic activity toward herring sperm DNA, was isolated from Asparagus officinalis seeds. The isolation procedure involved extraction with saline, (NH(4))(2)SO(4) precipitation, ion-exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion-exchange chromatography on CM-Sepharose, and FPLC gel filtration on Superdex 75. The doxyribonuclease was unadsorbed onto DEAE-cellulose and Affi-gel blue gel and adsorbed onto CM-Sepharose. It exhibited the novel N-terminal sequence, GIEVIKIREL. The deoxyribonuclease was purified to a specific activity of 1584 units/mg. It was devoid of ribonuclease, protease, and HIV-1 reverse transcriptase-inhibitory activities. However, it inhibited cell-free translation in a rabbit reticulocyte lysate system with an IC(50) of 20 microM. It exhibited antifungal activity toward Botrytis cinerea but not toward Fusarium oxysporum and Mycosphaerella arachidicola.

Amino Acid Sequence↗

PubMed2001

A Bowman-Birk-type trypsin-chymotrypsin inhibitor from broad beans.

An isolation procedure comprising affinity chromatography on Affi-gel blue gel, ion exchange chromatography on SP-Toyopearl, and fast protein liquid chromatography on Mono S was used to purify a peptide from broad beans which manifested antifungal activity toward Mycosphaerella arachidicola, Fusarium oxysporum, and Botrytis cinerea. The peptide demonstrated a molecular mass of 7.5 kDa. N-terminal sequence analysis disclosed the identity of the antifungal peptide to be a trypsin-chymotrypsin inhibitor. The trypsin-chymotrypsin inhibitor also exerted an inhibitory action on chymotrypsin activity and HIV-1 reverse transcriptase activity. Proliferation of murine splenocytes was stimulated in the presence of the trypsin-chymotrypsin inhibitor. This report constitutes the first observation of antifungal activity of a leguminous peptidic protease inhibitor.

Amino Acid Sequence↗

PubMed2001

Novel antifungal peptides from Ceylon spinach seeds.

Two novel antifungal peptides, designated alpha- and beta-basrubrins, respectively, were isolated from seeds of the Ceylon spinach Basella rubra. The purification procedure involved saline extraction, (NH(4))(2)SO(4) precipitation, ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose and FPLC-gel filtration on Superdex peptide column. alpha- and beta-basrubrins exhibited a molecular weight of 4.3 and 5 kDa, respectively. They inhibited translation in a rabbit reticulocyte system with an IC(50) value of 400 and 100 nM, respectively. alpha- and beta-basrubrin inhibited HIV-1 reverse transcriptase by (79.4 +/- 7.8)% and (54.6 +/- 3.6)%, respectively, at a concentration of 400 microM, and (10.56 +/- 0.92)% and (2.12 +/- 0.81)%, respectively, at a concentration of 40 microM. Both alpha- and beta-basrubrins exerted potent antifungal activity toward Botrytis cinerea, Mycosphaerella arachidicola, and Fusarium oxysporum.

Amino Acid Sequence↗

PubMed2001

Isolation of pleuturegin, a novel ribosome-inactivating protein from fresh sclerotia of the edible mushroom Pleurotus tuber-regium.

A ribosome-inactivating protein (RIP) designated pleuturegin, which inhibited translation in a cell-free rabbit reticulocyte lysate system with an IC50 of 0.5 nM, was purified from fresh sclerotia of the edible mushroom Pleurotus tuber-regium. Pleuturegin was distinguished from most plant and previously reported mushroom RIPs in that it was adsorbed on DEAE-cellulose and unadsorbed on SP-Sepharose, although all of them were adsorbed on Affi-gel blue gel. Pleuturegin demonstrated an N-terminal sequence that was different from those of RIPs from Flammulina velutipes (flammulin and velutin), Hypsizygus marmoreus (hypsin), and Lyophyllum shimeji (lyophyllin), the only mushroom RIPs with known N-terminal sequences. The molecular mass of pleuturegin was 38 kDa, similar to that of flammulin (40 kDa) but considerably larger than those of velutin (13.8 kDa), hypsin (20 kDa), and lyophyllin (20 kDa). Pleuturegin was devoid of ribonuclease activity.

Amino Acid Sequence↗

PubMed2001

Inhibition of human immunodeficiency virus type 1 reverse transcriptase, protease and integrase by bovine milk proteins.

Different proteins have been isolated from bovine milk including lactoferrin, lactoperoxidase, glycolactin, angiogenin-1, lactogenin, alpha-lactalbumin, lactoglobulin and casein. These proteins have been assayed for inhibitory activity against human immunodeficiency virus type 1 (HIV-1) reverse transcriptase, protease and integrase, enzymes crucial to the HIV-1 life cycle. It was found that different milk proteins inhibited the three aforementioned HIV enzymes to different extents. Lactoferrin strongly inhibited HIV-1 reverse transcriptase but only slightly inhibited HIV-1 protease and integrase. On the other hand, alpha-lactalbumin, beta-lactoglobulin and casein inhibited HIV-1 protease and integrase to an appreciable extent but did not inhibit HIV-1 reverse transcriptase. Glycolactin and angiogenin-1 suppressed the activity of HIV-1 reverse transcriptase by a moderate extent but more powerfully inhibited HIV-1 protease and integrase. In comparison with the other milk proteins glycolactin was a strong inhibitor of HIV-1 protease and integrase and a moderate inhibitor of HIV-1 reverse transcriptase. Lactogenin was a strong inhibitor of HIV-1 integrase, a moderate inhibitor of HIV-1 reverse transcriptase and a weak inhibitor of HIV-1 protease.

Animals↗

PubMed2001

First simultaneous isolation of a ribosome inactivating protein and an antifungal protein from a mushroom (Lyophyllum shimeji) together with evidence for synergism of their antifungal effects.

From the fruiting bodies of the mushroom Lyophyllum shimeji, a novel ribosome inactivating protein with a molecular weight of 20 kDa and exhibiting antifungal activity against Physalospora piricola (IC(50) = 2.5 microM) and Coprinus comatus was isolated. The protein, designated lyophyllin, was purified by ion exchange chromatography on CM-cellulose, affinity chromatography on Affi-gel Blue Gel, and then ion exchange chromatography on Mono S. Lyophyllin possessed an N-terminal sequence with some similarity to those of plant ribosome-inactivating proteins. It inhibited translation in rabbit reticulocyte lysate with an IC(50) of 1 nM, thymidine uptake by murine splenocytes with an IC(50) of 1 microM and HIV-1 reverse transcriptase activity with an IC(50) of 7.9 nM. Lyophyllin did not manifest ribonuclease or hemagglutinating activity. An antifungal protein, designated Lyophyllum antifungal protein (LAP), with a molecular weight of 14 kDa, and an N-terminal sequence somewhat analogous to those of angiosperm thaumatin-like proteins and thaumatins and an inactive variant of the ubiquitin-conjugating enzyme, was first isolated from Lyophyllum shimeji. LAP was adsorbed on CM-cellulose, Affi-gel blue gel, and Mono S. LAP exerted antifungal activity against P. piricola (IC(50) = 70 nM) and Mycosphaerella arachidicola but not against Rhizoctonia solani, Colletotrichum gossypii, and Coprinus comatus. It exerted very low translation inhibitory activity in a rabbit reticulocyte lysate system (IC(50) = 70 microM) and negligible ribonuclease activity toward yeast transfer RNA and hemagglutinating activity toward rabbit erythrocytes. It inhibited HIV-1 reverse transcriptase with an IC(50) of about 5.2 nM. A synergism in antifungal activities of LAP and lyophyllin against P. piricola was demonstrable.

Agaricales↗

PubMed2001

Hypsin, a novel thermostable ribosome-inactivating protein with antifungal and antiproliferative activities from fruiting bodies of the edible mushroom Hypsizigus marmoreus.

A novel ribosome-inactivating protein with a molecular weight of 20 kDa was isolated from fruiting bodies of the mushroom Hypsizigus marmoreus. The isolation procedure entailed ion exchange chromatography on CM-cellulose, affinity chromatography on Affi-gel Blue Gel and ion exchange chromatography on Mono Q. The protein designated hypsin demonstrated an inhibitory action against mycelial growth in various fungal species including Mycosphaerella arachidicola, Physalospora piricola, Fusarium oxysporum, and Botrytis cinerea with an IC50 of 2.7, 2.5, 14.2, and 0.06 microM, respectively. Translation in the rabbit reticulocyte lysate system was inhibited with an IC50 of 7 nM and HIV-1 reverse transcriptase activity was inhibited with an IC50 of 8 microM. Antiproliferative activity against mouse leukemia cells and human leukemia and hepatoma cells was observed. About 60% of the translation-inhibitory activity was retained after heating at 100 degrees C for 10 min. No loss of translation-inhibitory activity occurred after brief treatment with trypsin.

Agaricales↗

PubMed2001

Isolation of a novel thermolabile heterodimeric ribonuclease with antifungal and antiproliferative activities from roots of the sanchi ginseng Panax notoginseng.

An isolation procedure, consisting of ion exchange chromatography on CM-Sepharose, affinity chromatography on Affi-gel blue gel, and fast protein liquid chromatography on Mono S, was utilized to purify a base-nonspecific, heterodimeric ribonuclease (RNase) with diverse activities from roots of the sanchi ginseng Panax notoginseng. The RNase is unique in that it consists of two different nonglycoprotein subunits with a molecular weight of 27 and 29 kDa, respectively. The latter subunit is characterized by an N-terminal sequence showing remarkable similarity to that of the bitter gourd RNase. The Panax notoginseng RNase demonstrates potent RNase and translation-inhibitory activities. In addition, it exhibits antiproliferative activity toward leukemia L1210 cells and antifungal activity against Physalospora piricola and Coprinus comatus. Its RNase activity is not heat-resistant, unlike most RNases which are thermostable.

Animals↗

PubMed2001

Peptides from pinto bean and red bean with sequence homology to cowpea 10-kDa protein precursor exhibit antifungal, mitogenic, and HIV-1 reverse transcriptase-inhibitory activities.

Peptides with a molecular weight of 5 kDa have been isolated from seeds of the pinto bean and red bean, respectively. The peptides manifest an N-terminal sequence with remarkable resemblance to those of cowpea 10-kDa protein precursor and garden pea disease resistance response protein. The bean peptides possess potent antifungal activity toward a variety of fungal species including Botrytis cinerea, Mycosphaerella arachidicola, and Fusarium oxysporum. The proteins also demonstrate mitogenic activity toward mouse splenocytes and an inhibitory action on HIV-1 reverse transcriptase.

Amino Acid Sequence↗

PubMed2001

A novel lectin from Pseudostellaria heterophylla roots with sequence simularity to Kunitz-type soybean trypsin inhibitor.

From the roots of the Chinese medicinal herb Pseudostellaria heterophylla a single-chained lectin with a molecular weight of 36 kDa and high hemagglutinating activity was isolated. The lectin was adsorbed on DEAE-cellulose in 10 mM Tris-HCI buffer (pH 7.4) and was eluted by the same buffer containing 50 mM NaCl. It was adsorbed on SP-Sepharose in 10mM NH4OAc (pH 4.5) and eluted by approximately 0.5 M NaCl in the same buffer. The hemagglutinating activity of the lectin could not be inhibited by a large variety of monosaccharides, but was largely abrogated by exposure to 0.05 M HCl, 0.05M NaOH or 80 degrees C. However, about 50% of the activity remained after exposure to 0.025M NaOH or 40 degrees C. Despite possession of an N-terminal sequence exhibiting some similarity to thaumatin-like proteins with antifungal activity, the lectin was devoid of antifungal activity. The lectin exerted some inhibitory effect on the glycohydrolases alpha-glucosidase, beta-glucosidase and beta-glucuronidase which are involved in HIV infection but had no suppressive action on human immunodeficiency virus-type 1 reverse transcriptase.

Animals↗

PubMed2001

Isolation and characterization of velutin, a novel low-molecular-weight ribosome-inactivating protein from winter mushroom (Flammulina velutipes) fruiting bodies.

From the fruiting bodies of the edible mushroom Flammulina velutipes a single-chained ribosome inactivating protein with a molecular weight of 13.8 kDa was isolated with a procedure involving ion exchange chromatography on DEAE-cellulose and SP-Sepharose and affinity chromatography on Affi-gel blue gel. The protein was novel in that it possessed a molecular weight lower than those of previously reported RIPs and that it was capable of inhibiting human immunodeficiency virus (HIV-1) reverse transcriptase, beta-glucosidase and beta-glucuronidase. Its N-terminal sequence exhibited a certain degree of similarity to those of plant ribosome inactivating proteins.

Agaricales↗

PubMed2001

A comparison of HIV-1 integrase inhibition by aqueous and methanol extracts of Chinese medicinal herbs.

The aqueous and methanol extracts of twenty herbs traditionally used in Chinese medicine were screened for anti-HIV-1 integrase activity in a non-radioactive ELISA-based HIV-1 integrase assay. The screening was performed at an herb extract concentration of 50 microg/ml. It was found that most of the aqueous and methanol herb extracts could elicit strong inhibition of HIV-I integrase activity. The inhibition was most likely due to tannins or polyphenolics in the herb extracts. In most of the herb extracts, 40-80% of the anti-HIV-1 integrase activity could be removed after passing through a minicolumn of polyamide resin. After removal of polyphenolic compounds, the methanol extract of Paeonia suffruticosa still exerted potent inhibition of HIV-1 integrase (EC50 = 15 microg/ml) and the aqueous extract of Prunella vulgaris caused moderate inhibition (EC50 = 45 microg/ml). The results support the view that herbs represent a rich source of anti-HIV compounds.

Drugs, Chinese Herbal↗

PubMed2001

Panaxagin, a new protein from Chinese ginseng possesses anti-fungal, anti-viral, translation-inhibiting and ribonuclease activities.

From the roots of the Chinese ginseng Panax ginseng a protein designated panaxagin with ribonuclease activity, but possessing a sequence distinct from ribonucleases previously reported from ginseng calluses, was isolated. The purification protocol employed comprised extraction with cold saline, (NH4)2SO4 precipitation, 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 by fast protein liquid chromatography. The purified protein was composed of two identical subunits each with a molecular weight of 26 kDa. Its N-terminal amino acid sequence exhibits sites of similarity with the sequences of plant ribosome inactivating proteins and fungal ribonucleases. The spectrum of biological activities of panaxagin encompassed ribonuclease activity toward yeast transfer RNA, translation-inhibitory activity in a rabbit reticulocyte lysate system, and antifungal activity against fungi including Coprinus comatus and Fusarium oxysporum, but not against Rhizoctonia solani. In addition it displayed an inhibitory activity against human immunodeficiency virus reverse transcriptase and succinylation augmented this activity.

Amino Acid Sequence↗

PubMed2001

Isolation and characterization of a new ribosome inactivating protein, momorgrosvin, from seeds of the monk's fruit Momordica grosvenorii.

Momorgrosvin, a single-chained glycoprotein with a molecular weight of 27.7 kilodaltons and an isoelectric point of about 9 was isolated from the seeds of Momordica grosvenorii (Family Cucurbitaceae). The isolation procedure entailed acetone precipitation, affinity chromatography on Hi Trap Blue, cation exchange chromatography on Resource S and size exclusion chromatography on Superose 12. The sequence of the first eighteen N-terminal amino acid residues of momorgrosvin exhibited homology to those of RIPs from other Momordica species. Momorgrosvin inhibited protein synthesis in the rabbit reticulocyte lysate system with an IC50 of 0.3 nM and displayed RNA N-glycosidase activity giving rise to the diagnostic Endo's band at a concentration as low as 9 nM. The protein acted on tRNA to produce acid-soluble uv-absorbing species.

China↗

PubMed2001

Pineal indoles stimulate the gene expression of immunomodulating cytokines.

Male C57 mice received 10 consecutive daily intraperitoneal injections of melatonin, 5-methoxytryptamine or 5-methoxytryptophol (5mg/kg body weight). Control mice received the alcoholic saline vehicle. All mice were sacrificed 24 hours after the last injection. Following extraction of RNA from peritoneal exudate cells (PEC) and splenocytes, the level of gene expression was analyzed with the reverse transcription-polymerase chain reaction (RT-PCR). The results revealed that melatonin up-regulated the level of gene expression of transforming growth factor-beta (TGF-beta), macrophage-colony stimulating factor (M-CSF), tumor necrosis factor-alpha (TNF-alpha) and stem cell factor (SCF) in PEC, and the level of gene expression of interleukin-1beta (IL-1beta), M-CSF, TNF-alpha, interferon-gamma (IFN-gamma) and SCF in splenocytes. 5-Methoxytryptamine augmented the level of gene expression of TGF-beta, M-CSF and SCF in PEC, and the level of gene expression of IL-1beta, TNF-alpha, IFN-gamma, M-CSF and SCF in splenocytes. 5-Methoxytryptophol elevated the level of gene expression of TNF-alpha, IL-1beta, TGF-beta and M-CSF in PEC, and the level of gene expression of inducible nitric oxide synthase (iNOS), IL-1beta, M-CSF, TNF-alpha, IFN-gamma and SCF in splenocytes.

5-Methoxytryptamine↗