Biomedical subjects

K T Chu

Publications and source records attributed to K T Chu.

10 recordsLinked to original sources

PubMed2006

Smilaxin, a novel protein with immunostimulatory, antiproliferative, and HIV-1-reverse transcriptase inhibitory activities from fresh Smilax glabra rhizomes.

A protein, with a novel N-terminal amino acid sequence and a molecular mass of 30 kDa, was purified from fresh Smilax glabra rhizomes by adsorption on DEAE-cellulose, CM-cellulose, Con A-Sepharose, and Mono S, and by fast protein liquid chromatography-gel filtration on Superdex 75. The protein, designated as smilaxin, stimulated uptake of [methyl-3H]thymidine by murine splenocytes, peritoneal macrophages, and bone marrow cells, and production of nitric oxide by peritoneal macrophages. It inhibited uptake of [methyl-3H]thymidine by MBL2 and PU5 tumor cells but not uptake by S180 and L1210 cells. Smilaxin augmented glucose uptake into rat adipose tissue. It attenuated the activity of HIV-1-reverse transcriptase with an IC50 of 5.6 microM. However, it did not display hemagglutinating, antifungal or translation-inhibitory activities, indicating that it is not a lectin, an antifungal protein, or a ribosome-inactivating protein.

Animals↗

PubMed2005

Pleurostrin, an antifungal peptide from the oyster mushroom.

A 7kDa peptide, with inhibitory activity on mycelial growth in the fungi Fusaerium oxysporum, Mycosphaerella arachidicola and Physalospora piricola, was isolated from fresh fruiting bodies of the oyster mushroom. The isolation procedure entailed extraction with an aqueous buffer, ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel and gel filtration by fast protein liquid chromatography on Superdex 75. The protein was unadsorbed on DEAE-cellulose and adsorbed on Affi-gel blue gel. It demonstrated an N-terminal sequence different from known antifungal proteins and peptides.

Antifungal Agents↗

PubMed2005

A low-molecular mass ribonuclease from the brown oyster mushroom.

A ribonuclease, with a molecular mass of 9 kDa and an N-terminal sequence resembling the sequence of a fragment of tRNA/rRNA cytosine-C5-methylase and a fragment of a alanyl-tRNA synthetase, was isolated from fresh fruiting bodies of the brown oyster mushroom Pleurotus ostreatus. The ribonuclease was purified using a very simple protocol that comprised ion-exchange chromatography on carboxymethyl (CM)-cellulose and affinity chromatography on Affi-gel blue gel. Subsequent gel filtration by fast protein liquid chromatography on Superdex 75 and sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis revealed that the ribonuclease was purified after the first two chromatographic steps. The ribonuclease was adsorbed on CM-cellulose and Affi-gel blue gel. The ribonuclease exhibited the highest activity toward poly A, lower activity toward poly C, slight activity toward poly G, and indiscernible activity toward poly U. The enzyme was stimulated upon exposure to 1 microm Mg2+ and 10 microm Zn2+, but was inhibited by the following ions at 10 mm: Ca2+, Mg2+, Zn2+, Cu2+, Fe2+, Mn2+, and Fe3+. The ribonuclease required a pH of 8.0 and a temperature of 50-70 degrees C to express maximal activity. It had a Km of 60 microm toward yeast tRNA. It lacked mitogenic and HIV-1 reverse transcriptase inhibiting activities, but exerted antiproliferative activity toward leukemia L1210 cells.

Amino Acid Sequence↗

PubMed2004

Hydroxyapatite/PMMA composites as bone cements.

Currently PMMA is the polymer most commonly used as a bone cement for the fixation of total hip prostheses. Ideally, a bone cement material should be easy to handle, biologically compatible, nonsupporting of oral microbial growth, available in the particulate and molded forms, easy to obtain, nonallergenic, adaptable to a broad range of dental and medical applications, in possession of high compressive strength, and effective in guided tissue regenerative procedures. One of the problems associated with the conventional types of bone cement used is their unsatisfactory mechanical and exothermic reaction properties. The purpose of this in vitro study was to investigate and compare the mechanical properties (three-point bending strength, energy-to-break, and modulus of elasticity) and physical properties (setting time, water sorption, and exothermic heat) of HA/PMMA (HA group) and bovine-bone originated HA/PMMA (BB group) composites. Composites samples were fabricated by admixing method. It was found that the addition of HA and BB particles increased the water sorption. Generally 10 v/o 20 v/o HA and 0 v/o to 10 v/o BB ratio combinations had significant beneficial effects on the mechanical properties. The heat generated during polymerization was influenced by the different admixtures. More than 40 v/o HA and 40 v/o BB should be mixed into PMMA to reduce the peak temperature. Overall evaluation indicated that the BB group had better properties than the HA group.

Bone Cements↗

PubMed2003

Isolation of a large thaumatin-like antifungal protein from seeds of the Kweilin chestnut Castanopsis chinensis.

A protein with an N-terminal sequence showing a much lesser extent of homology than French bean and kiwi fruit thaumatin-like proteins (TLPs) to other TLPs, and possessing a molecular mass of 30 kDa which is considerably higher than those of previously reported TLPs, has been purified from the seeds of the chestnut Castanopsis chinensis Hance. The protein was unadsorbed on DEAE-cellulose in 10 mM Tris-HCl buffer (pH 7.3), and adsorbed on Affi-gel blue gel in the same buffer, on CM-cellulose in 10 mM ammonium acetate buffer (pH 4.5), and on Mono S in 20 mM ammonium acetate buffer (pH 5.5). A highly purified protein preparation was obtained after fractionation on the first three chromatographic media. Castanopsis TLP appeared as a single band (30 kDa) in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and as a single peak (30 kDa) in gel filtration on Superdex 75 by fast protein liquid chromatography. The TLP exerted antifungal activity against Botrytis cinerea, Fusarium oxysporum, Mycosphaerella arachidicola, and Physalospora piricola, with an IC(50) of 0.5 microM against F. oxysporum. Castanopsis TLP was more potent than French bean and kiwi fruit TLPs in its antifungal activity toward F. oxysporum and M. arachidicola. The antifungal activity of Castanopsis TLP remained essentially unaltered after incubation at 40 degrees C for 10 min, was reduced after incubation at 60 degrees C, and disappeared after treatment at 80 degrees C. The antifungal activity underwent a decline after treatment with trypsin (enzyme:substrate ratio 1:100) at 37 degrees C for 1h but some activity remained. Castanopsis TLP exhibited a much more potent inhibitory activity on HIV-1 reverse transcriptase (IC(50) = 1.6 microM) than kiwi fruit TLP (IC(50) > or = 27 microM). Castanopsis TLP was obtained with a yield of 20 mg from 1 kg chestnut seeds.

Amino Acid Sequence↗

PubMed2003

Cicerarin, a novel antifungal peptide from the green chickpea.

A peptide designated cicerarin, with an N-terminal amino acid sequence VKSTGRADDDLAVKTKYLPP dissimilar from known proteins and peptides and a molecular mass of 8kDa, was isolated from seeds of the green chickpea Cicer arietinum cv green chickpea. Cicerarin was isolated with a procedure that involved ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, and gel filtration by fast protein liquid chromatography on Superdex 75. Cicerarin was unadsorbed on DEAE-cellulose and adsorbed on Affi-gel blue gel in 10mM Tris-HCl buffer (pH 7.3). Cicerarin exerted antifungal activity against Botrytis cinerea, Mycosphaerella arachidicola, and Physalospora piricola. The antifungal activity was preserved after exposure to 100 degrees C for 15min.

Amino Acid Sequence↗

PubMed2003

Mollisin, an antifungal protein from the chestnut Castanea mollissima.

The isolation of a protein designated mollisin, with an N-terminal sequence manifesting some similarity to thaumatin-like proteins (TLPs), and possessing a molecular mass of 28 kDa which is higher than those of TLPs, is reported herein from the seeds of the chestnut Castanea mollisima. The protein was unadsorbed on DEAE-cellulose, and adsorbed on Affi-gel blue gel and Mono S. Mollisin exhibited a molecular mass of 28 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis as well as in gel filtration on Superdex 75 by fast protein liquid chromatography. The protein inhibited mycelial growth in Fusarium oxysporum, Mycosphaerella arachidicola and Physalospora piricola, with an IC (50) of 0.83 microM, 6.48 microM and 9.21 microM, respectively. Mollisin displayed a higher antifungal potency than French bean and kiwi fruit TLPs toward F. oxysporum and M. arachidicola. The antifungal activity of mollisin was unaffected by incubation at 40 degrees C for 10 minutes, underwent a decline after incubation at 60 degrees C, and was completely abolished after treatment at 80 degrees C. Mollisin exhibited a more potent inhibitory activity on HIV-1 reverse transcriptase than kiwi fruit TLP.

Amino Acid Sequence↗

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↗

PubMed1991

TEF, a transcription factor expressed specifically in the anterior pituitary during embryogenesis, defines a new class of leucine zipper proteins.

We have identified and characterized a new member of the leucine zipper (bZIP) gene family of transcription factors, thyrotroph embryonic factor (TEF). Analysis of the ontogeny of TEF gene expression reveals the presence of TEF transcripts, beginning on embryonic day 14, only in the region of the rat anterior pituitary gland in which thyrotrophs arise. This pattern of gene expression corresponds temporally and spatially to the onset of thyroid-stimulating hormone (TSH beta) gene expression, which defines the thyrotroph phenotype. Coupled with this observation, we find that TEF can bind to and trans-activate the TSH beta promoter. In contrast to this restricted pattern of expression during embryogenesis, TEF transcripts appear in several tissues in the mature organism. We propose that TEF belongs to a new class of bZIP proteins on the basis of the unique homology between TEF and another member of the bZIP gene family, the albumin D box-binding protein (DBP). TEF and DBP transcripts are coexpressed in a pituitary cell line, and these two proteins can readily form heterodimers. The DNA-binding and dimerization domains of TEF correspond to those found in other bZIP proteins. We have however, identified a cluster of basic amino acids, found only in TEF and DBP, that is necessary for the proper DNA-binding site specificity of TEF. A major trans-activation domain of TEF resides outside the region of homology to other bZIP proteins. These data are consistent with a role for a member of a new class of bZIP transcription factors in activating gene expression in the developing thyrotroph.

Amino Acid Sequence↗

PubMed1986

A micromethod for measuring swine fever antibody by neutralisation and immunofluorescence.

A micromethod employing the neutralisation and direct immunofluorescence technique for the detection of antibodies against swine fever in pig serum samples is described. The micromethod is simple and reproducible when compared with the macromethod. A total of 80 blood samples were randomly collected for comparison. The results are promising and reveal a 100 per cent correlation with the macrotechnique.

Animals↗