Biomedical subjects

Ting-Jun Fan

Publications and source records attributed to Ting-Jun Fan.

9 recordsLinked to original sources

PubMed2006

Purification and characterization of hatching enzyme from shrimp Penaeus chinensis.

By using Penaeus chorion as a specific substrate, the hatching enzyme (HE) from Penaeus chinensis was purified by gel-filtration and ion-exchange chromatography, and characterized in terms of its molecular weight and enzymatic properties in this study. It was found that the molecular weight of Penaeus HE is about 43.0 kDa in SDS-PAGE. The Penaeus HE had obvious choriolytic activity, which was optimal at pH 6.0 and temperature of 40 degrees C, respectively. The Km value of the HE for casein was 7.47 mg ml(-1). The HE activity was almost completely inhibited by SBTI, p-APMSF, bestatin, and NEM, greatly inhibited by ovomucoid, TLCK, IAM, chymostatin, and PMSF, and slightly inhibited by pepstatin A, TPCK, LBTI, and leupeptin. These results indicate that the HE is most probably a trypsin-type serine protease. Besides of these, the HE was extremely sensitive to EDTA, Zn2+, Ca2+, Mg2+, and Cu2+. Combined with the results that the EDTA-pretreated HE activity could be perfectly recovered by Zn2+, it is indicated that shrimp HE is most probably a kind of Zn-metalloprotease.

Animals↗

PubMed2005

Caspase family proteases and apoptosis.

Apoptosis, or programmed cell death, is an essential physiological process that plays a critical role in development and tissue homeostasis. The progress of apoptosis is regulated in an orderly way by a series of signal cascades under certain circumstances. The caspase-cascade system plays vital roles in the induction, transduction and amplification of intracellular apoptotic signals. Caspases, closely associated with apoptosis, are aspartate-specific cysteine proteases and members of the interleukin-1beta-converting enzyme family. The activation and function of caspases, involved in the delicate caspase-cascade system, are regulated by various kinds of molecules, such as the inhibitor of apoptosis protein, Bcl-2 family proteins, calpain, and Ca2+. Based on the latest research, the members of the caspase family, caspase-cascade system and caspase-regulating molecules involved in apoptosis are reviewed.

Animals↗

PubMed2003

Apoptosis-inducing factor and apoptosis.

Apoptosis-inducing factor (AIF) is a phylogenetically conserved mitochondrial intermembrane flavoprotein which has the ability to induce apoptosis via a caspase-independent pathway. AIF plays an important role in inducing nuclear chromatin condensation as well as large-scale DNA fragmentation (approximately 50 kb), and is essential for programmed cell death during cavitation of embryoid bodies. Two homologous proteins, AIF-homologous mitochondrion-associated inducer of death (AMID) and p53-responsive gene 3 (PRG3), also have apoptosis-inducing effects. Recent studies on mechanisms of AIF-mediated apoptotic DNA degradation in Caenorhabditis elegans reveal that WAH-1(an AIF homolog in C. elegans) induced apoptosis is CED-3-dependent. AIF also interacts with cytochrome c and caspases during mammalian apoptosis processes, indicating that different apoptotic pathways may be mutually cross-regulated to activate an apoptotic program.

Animals↗

PubMed2002

[Advances in fish antifreeze protein research].

Antifreeze proteins (AFPs) can highly effectively protect cells and embryos from damages in freezing process by lowering the freezing points of their cytoplasmic matrix and body fluids in a noncolligative manner. Based on their origins and properties, AFPs have been classified into four types, i.e. type I, II, III and IV. Each of them possesses rather distinct characteristics both in structure and composition, although all of them have ability of lowering freezing points of fluids. AFPs' genes have been characterized as members of a multigene family and the levels of their mRNA synthesis vary significantly with seasons. Adsorption-inhibition operating at the ice surface is nowadays a hypothesis widely used to interpret the molecular mechanisms of noncolligative lowering of the freezing point, but the details of the mechanism on how the different types of AFP are adsorbed onto ice remain uncertain. Progresses in research on structures, amino acid compositions, genes, antifreeze mechanisms of the 4 distinct types of AFPs, and the application of the AFPs in cryopreservation of cells and embryos are reviewed here.

Animals↗

PubMed2002

Bcl-2 family proteins and apoptosis.

Bcl-2 family proteins play key roles in apoptosis. They coordinate with other apoptotic proteins in apoptosis to control mitochondria stability both in structure and function, while mitochondria probably act as the main switch of apoptosis. Bcl-2 family proteins can be divided into two types, antiapoptotic proteins and pro-apoptotic proteins. During apoptosis, Bcl-2 family proapoptotic proteins can translocate to the outer membrane of mitochondrion after posttranslational modification by certain proteases such as caspases. Then cytochrome c (cyt.c), apoptosis-inducing factors (AIFs), and other proapoptotic factors are released from mitochondrion, triggering apoptosis. Bcl-2 family antiapoptotic proteins sequestered in mitochondrion have ability to inhibit the release of cyt.c and AIFs, and prevent apoptosis. When interacting with activated proapoptotic proteins, the antiapoptotic proteins lose inhibiting ability of pro-apoptotic factors' release, and again triggering apoptosis. Based on the newest research evolvements, types, structures, localizations, apoptosis regulating mechanisms of Bcl-2 family proteins are reviewed.

Animals↗

PubMed2002

[Purification and partial biochemical characterization of phenoloxidase from Penaeus chinensis].

Using L-DOPA as a probe, phenoloxidase (PO) from Penaeus chinensis hemolymph was purified by gel-filtration and ion-exchange chromatography, and characterized in terms of its molecular weight and enzymatic properties in this study. It was found that prophenoloxidase (proPO) isolated as monomeric protein had a molecular weight of 87.5 kD, and a 77 kD phenoloxidase molecule was often contained in preparations. The 87.5 kD proPO had a very low enzymatic activity on 0.02 mmol/L L-DOPA, whereas the 77 kD PO had a very high enzymatic activity on L-DOPA. Enzymatic activity of PO against L-DOPA was optimal at pH 6.0, temperature of 40 degrees, and with an apparent K(m) value of 1.99 mmol/L. The PO activity was extremely sensitive to ascorbic acid, cysteine and dithiothreitol, very sensitive to thio urea, however not sensitive to sodium sulfite, citric acid and benzoic acid, confirmed that it was a phenoloxidase, combined with its specific oxidase activity on substrate of monophenol and L-DOPA, indicate that it was a tyrosinase type phenoloxidase. This enzyme is very sensitive to EDTA and metal ions, its activity is strongly enhanced by Mg(2+) and strongly inhibited by Cu(2+), which indicates that this PO is probably a kind of metalloenzyme.

Acrylic Resins↗

PubMed2001

Mitochondrion and Apoptosis.

Mitochondrion is not only the major ATP manufacture center of animal cells, but also plays a key role, as a main switch, in the regulation of apoptos is. Opening of the mitochondrion permeability transition pore (MPTP), the life-or-death switch of cells, causes an increase of the permeability of mitochondrial membrane and the release of several types of apoptogenic factors from the intermembrane space, such as cytochrome c, apoptosis inducing factors (AIFs),procaspases and Ca(2+). These apoptotic factors can either activate caspases, the main member of apoptotic proteins, or destruct independently the intranuclear chromatin, or interact with other Ca(2+) -dependent proteins. These result in structural rupture and dysfunction of cells, and the cells are finally degraded into apoptotic bodies and died. Studies on the regulation mechanisms of mitochondrion in apoptosis will be of great value theoretically as well as potential practical usage in designing drugs for cancer, Parkinson's disease and so on, using mitochondria as targets. To understand the key role of the mitochondrion in the determination of life and death of the cells, recent findings in this field are reviewed in this article.

Journal Article↗

PubMed1998

Purification and Biochemical Characterization of the Hatching Enzyme from Xenopus laevis.

Using anti-GST-UVS.2 antibody and vitellin envelope (VE) as probes, the Xenopus laevis hatching enzyme (HE) was purified about 90-fold over the starting crude HE by gel-filtration and ionexchange chromatography, and its enzymatic and biochemical properties were studied. The HE has a molecular weight of 60 kD, and has high proteolytic and VE-solubilizing activities. It was very unstable during purification, and was digested easily into a 40 kD molecule, which had no VE-solubilizing activity, but still retained its proteolytic activity. The 40 kD molecule probably represents only the main protease domain in the 60 kD molecule, with two CUB repeats lost. The results on its sensitivity to EDTA and some other metal ions, combined with the occurrence of the astacin family metalloprotease-specific "HExHxxGFxHE" sequence in the deduced HE amino acid sequence, indicate that the HE is a metalloprotease. HE is very sensitive to trypsin-specific inhibitors such as leupeptin, p-APMSF, SBTI, LBTI, ovomucoid, bestatin, DFP and TLCK, which indicates that it is a trypsin-type protease. Boc-Leu-Gly-Arg-MCA had been determined to be its specific MCA-substrate.

Journal Article↗

PubMedDate not supplied

Initiation of cartilage cell culture from skate (Raja porasa Günther).

Cartilage tissues from the proboscis of skate (Raja porasa Günther) were used to initiate primary cultures of cartilage cells. Aseptically dissected cartilage tissues were immersed in MEM medium free of fetal bovine serum (FBS), pH 7.6, and minced into small pieces (1 mm3 on average). After hydrolysis with collagenase II, hyaluronidase, and trypsin for 2 hours at room temperature, the acquired cartilage cells were rinsed twice with 20% FBS-supplemented MEM medium and then inoculated into 25-cm3 cell culture flasks, and incubated at 24 degrees C. The primary cultures were initiated successfully, and the cartilage cells grew gradually into a confluent monolayer at day 10. Effects of growth factors were also tested in this study, and it was found that 20 ng/ml of basic fibroblast growth factor and 100 ng/ml of insulin-like growth factor II together had the most prominent stimulating effect on the growth and division of cartilage cells in the series of concentration combinations employed. The induced cartilage cells cultured formed a confluent monolayer at day 7.

Animals↗