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Biomedical subjects

J S Yoo

Publications and source records attributed to J S Yoo.

At least 19 recordsLinked to original sources
PubMed2006

Cloning, purification, and characterization of chitosanase from Bacillus sp. DAU101.

A chitosanase-producing Bacillus sp. DAU101 was isolated from Korean traditional food. This strain was identified on the basis of phylogenetic analysis of the 16S rDNA sequence, gyrA gene, and phenotypic analysis. The gene encoding chitosanase (csn) was cloned and sequenced. The csn gene consisted of an open reading frame of 837 nucleotides and encodes 279 amino acids with a deduced molecular weight of 31,420 Da. The deduced amino acid sequence of the chitosanase from Bacillus sp. DAU101 exhibits 88 and 30 % similarity to those from Bacillus subtilis and Pseudomonas sp., respectively. The chitosanase was purified by glutathione S-transferase fusion purification system. The molecular weight of purified enzyme was about 27 kDa, which suggests the deletion of a signal peptide by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The pH and temperature optima of the enzyme were 7.5 and 50 degrees C, respectively. The enzyme activity was increased by about 1.6-fold by the addition of 5 or 10 mM Ca(2+). However, Hg(2+) and Ni(+) ions strongly inhibited the enzyme. The enzyme produced, GlcN(2-4), were the major products from a soluble chitosan.

Amino Acid Sequence↗
PubMed2004

Effects of basic oxygen furnace slag and inorganic nutrients on the germination of resting cysts of two toxic dinoflagellates.

Effects of basic oxygen furnace (BOF) slag, inorganic nutrients and H2S on the germination of resting cysts of two toxic dinoflagellates Alexandrium catenella/tamarense and Gymnodinium catenatum were studied in batch cultures. The germination rate of the test species has increased by 23-25%, when the concentration of NO3--N or H2S in culture medium has increased to 2.0 ppm. At the treatment of enriched NH4+-N and PO43--p, the germination of resting cyst was increased. Nevertheless, the increased range in germination rates was less than those of NO3--N and H2S. When BOF slag in culture medium increased to 50 mg/ml (or 500 g/m2), the cyst germination rate fell to less than 5%. At higher level of concentrations germination was completely inhibited. Adding BOF slag to the culture medium reduced the concentration of inorganic salts and H2S in seawater and sediments, resulting in the inhibition of cyst germination. These findings demonstrate the potential use of BOF slag on the sediments seed bank of red tide organism because it has an ability to inhibit resting cysts germination.

Animals↗
PubMed2004

Use of sodium transfer tissue biosensor (STTB) for monitoring of marine toxic organism.

A highly sensitive sodium (Na+) transfer tissue biosensor (STTB) was designed using a frog bladder membrane to measure paralytic shellfish poisons (PSP). The STTB consists, of a Na+ electrode covered by the membrane, which was then integrated into a flow-through system for continuous measurements. In the absence of Na+ channel blocker, active transfer of Na+ occurred from inside to outside across the frog membrane. When the STTB was used to measure the Na+ -dependent dissociation of PSP, it was able to detect PSB at a level contained in a single cell. However, 5 fg or higher (100 cells or more) is needed for accurate and reproducible measurements. The toxicity obtained by the STTB was significantly correlated (r = 0.9449) to that determined by the HPLC. Therefore, the simple method of the STTB can be used not only to detect a low level PSP in toxic plankton populations, but also to monitor poisons in shellfish.

Animals↗
PubMed2001

Augmented expression of peroxiredoxin I in lung cancer.

Comparative proteome analysis was performed between human normal (BEAS 2B) and malignant (A549) lung epithelial cells in an attempt to identify novel biomarkers of lung cancer. Approximately 500 protein spots could be separated by mini two-dimensional electrophoresis and visualized with Coomassie blue R-250. Among those relatively abundant proteins, eight spots were changed more than twofold reproducibly and identified by peptide mass fingerprints using mass spectrometry and database search. The increased proteins in A549 were aldehyde dehydrogenase, peroxiredoxin I, fatty acid binding protein, aldoketoreductase, and destrin, whereas the decreased proteins were galectin-1, transgelin, and stathmin. Since human lung is exposed to continuous oxidative stress, antioxidant enzyme peroxiredoxin I was selected for further investigation and its augmented expression was confirmed in cancer tissues compared to normal tissues from lung cancer patients, suggesting peroxiredoxin I as a potential biomarker of lung cancer.

Amino Acid Sequence↗
PubMed2001

Solution structure of the SL1 RNA of the M1 double-stranded RNA virus of Saccharomyces cerevisiae.

The 20-nucleotide SL1 VBS RNA, 5'-GGAGACGC[GAUUC]GCGCUCC (bulged A underlined and loop bases in brackets), plays a crucial role in viral particle binding to the plus strand and packaging of the RNA. Its structure was determined by NMR spectroscopy. Structure calculations gave a precisely defined structure, with an average pairwise root mean square deviation (RMSD) of 1.28 A for the entire molecule, 0.57 A for the loop region (C8-G14), and 0.46 A for the bulge region (G4-G7, C15-C17). Base stacking continues for three nucleotides on the 5' side of the loop. The final structure contains a single hydrogen bond involving the guanine imino proton and the carbonyl O(2) of the cytosine between the nucleotides on the 5' and 3' ends of the loop, although they do not form a Watson-Crick base pair. All three pyrimidine bases in the loop point toward the major groove, which implies that Cap-Pol protein may recognize the major groove of the SL1 loop region. The bulged A5 residue is stacked in the stem, but nuclear Overhauser enhancements (NOEs) suggest that A5 spends part of the time in the bulged-out conformation. The rigid conformation of the upper stem and loop regions may allow the SL1 VBS RNA to interact with Cap-Pol protein without drastically changing its own conformation.

Base Sequence↗
PubMed2001

Serum factors associated with neovascular glaucoma following vitrectomy for proliferative diabetic retinopathy.

We performed a retrospective study of serum factors associated with neovascular glaucoma that can occur following vitrectomy for proliferative diabetic retinopathy. The medical records of 183 patients (241 eyes) who received vitrectomy between August 1996 and August 2000 were studied retrospectively and subsequently analyzed by linear logistic regression analysis and multiple logistic regression tests. Neovascular glaucoma developed at an average of 2.7 months in 31 of 241 eyes (14.1%). The overall anatomical success rate of retinal attachment was 82.5% (199 eyes in 241 eyes), although it decreased to 45.1% (14 eyes in 31 eyes) in eyes with neovascular glaucoma. Serum cholesterol (P = 0.041) and fibrinogen levels (P = 0.020) were significantly associated with the development of neovascular glaucoma. However, no significant association could be found concerning hypertension, diabetic retinopathy or hypercholesterolemia (P > 0.05). We suggest that serum creatinine, cholesterol and fibrinogen levels can be used to predict the development of neovascular glaucoma in vitrectomized eyes with diabetic retinopathy and can further provide a more active approach to preventing the development of this condition.

Adult↗
PubMed2000

Proteome analysis of light-induced proteins in Synechocystis sp. PCC 6803: identification of proteins separated by 2D-PAGE using N-terminal sequencing and MALDI-TOF MS.

The cyanobacterium Synechocystis sp. PCC 6803 is an ideal model organism for the proteome study of light-induced gene expression because the whole genomic sequence has been determined. The soluble proteins extracted from light- and dark-cultured cells were separated by two-dimensional polyacrylamide gel electrophoresis. Light-induced protein spots electroblotted on a polyvinyldiene difluoride membrane were analyzed by N-terminal Edman sequence determination and followed by CyanoBase. The tryptic digests of some proteins were also confirmed by matrix-assisted laser desorption ionization/time-of-flight (MALDI-TOF) and MS-Fit search. Interestingly, eight proteins were related to photosynthesis and respiration (RbcS/L, CbbA, Gap2, AtpB, CpcB, PsbO, and PsbU). Four proteins (SodB, DnaK, GroEL2, and Tig) were involved in cellular processes and the functions of another two proteins (rehydrin and membrane protein) were unknown. The proteome analysis by N-terminal Edman sequencing and MALDI-TOF enabled us to characterize one-shot protein profiles expressed under different physiological conditions.

Amino Acid Sequence↗
PubMed2000

Cardiac phospholipase D2 localizes to sarcolemmal membranes and is inhibited by alpha-actinin in an ADP-ribosylation factor-reversible manner.

Myocardial phospholipase D (PLD) has been implicated in the regulation of Ca(2+) mobilization and contractile performance in the heart. However, the molecular identity of this myocardial PLD and the mechanisms that regulate it are not well understood. Using subcellular fractionation and Western blot analysis, we found that PLD2 is the major myocardial PLD and that it localizes primarily to sarcolemmal membranes. A 100-kDa PLD2-interacting cardiac protein was detected using a protein overlay assay employing purified PLD2 and then identified as alpha-actinin using peptide-mass fingerprinting with matrix-assisted laser desorption/ionization mass spectroscopy. The direct association between PLD2 and alpha-actinin was confirmed using an in vitro binding assay and localized to PLD2's N-terminal 185 amino acids. Purified alpha-actinin potently inhibits PLD2 activity (IC(50) = 80 nm) in an interaction-dependent and ADP-ribosylation factor-reversible manner. Finally, alpha-actinin co-localizes with actin and with PLD2 in the detergent-insoluble fraction from sarcolemmal membranes. These results suggest that PLD2 is reciprocally regulated in sarcolemmal membranes by alpha-actinin and ARF1 and accordingly that a major role for PLD2 in cardiac function may involve reorganization of the actin cytoskeleton.

Actinin↗
PubMed2000

Reaction monitoring of succinylation of collagen with matrix-assisted laser desorption/ionization mass spectrometry.

Succinylated collagen was synthesized by the reaction of collagen with succinic anhydride under basic conditions for one hour. Using the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) technique, the reaction products were directly identified without multi-step separation processes. MALDI-MS monitored the reaction more accurately than the conventional method of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). From the change in molecular mass during the reaction, it is observed that about 28 succinyl groups are attached to the collagen strand.

Animals↗
PubMed2000

Stage-specific assays to study biosynthetic cargo selection and role of SNAREs in export from the endoplasmic reticulum and delivery to the Golgi.

To analyze the role of coat protein type II (COPII) coat components and targeting and fusion factors in selective export from the endoplasmic reticulum (ER) and transport to the Golgi, we have developed three novel, stage-specific assays. Cargo selection can be measured using a "stage 1 cargo capture assay," in which ER microsomes are incubated in the presence of glutathione S-transferase (GST)-tagged Sar1 GTPase and purified Sec23/24 components to follow recruitment of biosynthetic cargo to prebudding complexes. This cargo recruitment assay can be followed by two sequential assays that measure separately the budding of COPII-coated vesicles from ER microsomes (stage 2) and, finally, delivery of cargo-containing vesicles to the Golgi (stage 3). We show how these assays provide a means to identify the snap receptor (SNARE) protein rBet1 as an essential component that is not required for vesicle formation, but is required for vesicle targeting and fusion during ER-to-Golgi transport. In general, these assays provide an approach to characterize the biochemical basis for the recruitment of a wide variety of biosynthetic cargo proteins to COPII vesicles and the role of different transport components in the early secretory pathway of mammalian cells.

Biological Transport↗
PubMed2000

Association of HLA with Vogt-Koyanagi-Harada syndrome in Koreans.

PURPOSE: To study the distribution of human leukocyte antigen HLA-A/B antigens and HLA-DR/-DQ/-DP alleles and to investigate the immunogenetic background of Korean patients with Vogt-Koyanagi-Harada (VKH) syndrome and clinical course with different types of HLA. METHODS: Human leukocyte antigen typings were performed in 18 Korean patients with VKH syndrome and in 128 healthy control subjects. HLA-A/B loci serologic typing was performed according to the standard microlymphocytotoxicity technique. DNA was extracted through the salting out method, and HLA-DR phenotyping and HLA-DR4, HLA-DQ, and HLA-DP subtyping were performed with the polymerase chain reaction-sequence specific oligonucleotide probe (PCR-SSOP) method. RESULTS: Among HLA-A/B antigens typed by the standard microlymphocytotoxicity method, the frequencies of HLA-A31 (RR = 6.1, P<1x10(-2)) and HLA-B55 (RR = 15.8, P<.05) were significantly increased in the patient group compared with the control group. Among HLA-DR/-DQ/-DP alleles subtyped by DNA methods, the frequencies of HLA-DRB1*04 (RR = 45.1, P<1x10(-7)) and HLA-DRB1*07 (RR = 3.2, P<.05) were significantly increased. However, significant decreases in HLA-DRB1*08 (RR = .1, P<.05), HLA-DRB1*13 (RR = .1, P<.05), and HLA-DRB1*14 (RR = .1, P<.05) frequencies were observed. The result of HLA-DR, HLA-DQ, and HLA-DP subtyping showed the significant increase in DRB1*0405 (RR = 45.1, P<1x10(-7)), DQA1*0302 (RR = 12.0, P<1x10(-4)), DQB1*0303 (RR = 5.0, P<1x10(-2)), DQB1*0401 (RR = 18.9, P<1x 10-6), and DPB1*0501 (RR = 3.8, P<.05). However, significant decreases in DQA1*0101 (RR = .1, P< .05), DQA10102 (RR = .1, P<1x10(-2)), DQA1*0103 (RR = .1, P<.05), DQA1*0501 (RR = .1, P<1x10(-2)), DQB1*0301 (RR = .1, P<.05), DQB1*0601 (RR = .1, P<.05), DPB1*0201 (RR = .3, P<.05), and DPB1*0401 (RR = .1, P<.05) frequencies were also observed. In patients with DRB1*0405 itself or HLA-DRB1*0405-DQA1*0302-DQB1*0401 haplotype, a reduction in visual acuity and ocular complications was common. CONCLUSIONS: These results suggest that HLA-DRB1*0405 itself or HLA-DRB1*0405-DQA1*0302-DQB1*0401 haplotype is greatly increased and may play the most important role in the development and the clinical course of VKH syndrome in Korean patients.

Alleles↗
PubMed2000

Application of a channel biosensor for toxicity measurements in cultured Alexandrium tamarense.

The purpose of this study is to examine the toxicity of Alexandrium tamarense strains using a channel biosensor. With this biosensor, we were able to measure very small quantities of PSP toxin contained within an individual plankton cell. However, measurement of at least 100 cells is more desirable for increasing the sensitivity of the assay. Therefore, in the near future, the proposed biosensor system may be used for monitoring the STX (saxitoxin) produced by a few naturally toxic phytoplankton, and also measuring small amounts of toxin in shellfish.

Biological Assay↗
PubMed1999

Phosphorylation and activation of phospholipase D1 by protein kinase C in vivo: determination of multiple phosphorylation sites.

Protein kinase C (PKC) is an important regulator of phospholipase D1 (PLD1). Currently there is some controversy about a phosphorylation-dependent or -independent mechanism of the activation of PLD1 by PKC. To solve this problem, we examined whether PLD1 is phosphorylated by PKC in vivo. For the first time, we have now identified multiple basal phophopeptides and multiple phorbol myristate acetate (PMA) induced phosphopeptides of endogenous PLD1 in 3Y1 cells as well as of transiently expressed PLD1 in COS-7 cells. Down regulation or inhibition of PKC greatly attenuated the PMA-induced phosphorylation as well as the activation of PLD1. In the presence of PMA, purified PLD1 from rat brain was also found to be phosphorylated by PKCalpha in vitro at multiple sites generating seven distinct tryptic phosphopeptides. Four phosphopeptides generated in vivo and in vitro correlated well with each other, suggesting direct phosphorylation of PLD1 by PKCalpha in the cells. Serine 2, threonine 147, and serine 561 were identified as phosphorylation sites, and by mutation of these residues to alanine these residues were proven to be specific phosphorylation sites in vivo. Interestingly, threonine 147 is located in the PX domain and serine 561 is in the negative regulatory "loop" region of PLD1. Mutation of serine 2, threonine 147, or serine 561 significantly reduced PMA-induced PLD1 activity. These results strongly suggest that phosphorylation plays a pivotal role in PLD1 regulation in vivo.

Amino Acid Sequence↗
PubMed1999

Structural identification of glycerolipid molecular species isolated from cyanobacterium Synechocystis sp. PCC 6803 using fast atom bombardment tandem mass spectrometry.

Our previous works have demonstrated that fast atom bombardment tandem mass spectrometry can be a valuable tool in determining the complete structure of glycoglycerolipids and glycerophospholipids. Collision-induced dissociation of sodium-adducted molecular ions ([M + Na]+ or [M - H + 2Na]+) generates diverse product ions informative on the double-bond position in fatty acyl groups as well as the polar head group and fatty acid composition. Here we report that this direct and rapid method can be applied to the structural determination of individual molecular species of each glycerolipid class purified from the total lipid extract of cyanobacterium Synechocystis sp. PCC 6803. Especially, based on the preference for the loss of the fatty acyl group positioned at the sn-2, it was proved that all of the molecular species of diacylglycerolipids contained a palmitoyl group exclusively at the sn-2 position. Additionally, lysoglycerolipids, monoacyl forms of four major membrane diacylglycerolipids, were first isolated together from a fresh extract. Using fast atom bombardment mass spectrometry and tandem mass spectrometry, it was found that each lysoglycerolipid had a molecular species with only palmitic acid as a fatty acyl group. Thus, these compounds could be synthesized by specific enzyme-catalyzed hydrolysis of the sn-1 fatty acyl group of the corresponding diacylglycerolipids.

Cyanobacteria↗
PubMed1999

Selective inactivation of protein tyrosine phosphatase PTP1B by sulfone analogue of naphthoquinone.

Protein tyrosine phosphatase inactivators are of interest as research tools and as therapeutic agents. In this study, the effect of sulfone analogue of naphthoquinone on the activities of PTP1B and other PTPs was examined. The results indicated that this compound selectively and irreversibly inactivated the PTP1B with the dissociation constant Ki of 3.5 microM and the inactivation rate constant kinact of 2.2 x 10(-2) sec-1.

Binding Sites↗
PubMed1999

Functional implications of genetic interactions between genes encoding small GTPases involved in vesicular transport in yeast.

Ras-related, guanine nucleotide-binding proteins of the Ypt/Rab family play a key role at defined steps in vesicular transport, both in yeast and in mammalian cells. In yeast, Ypt1p has an essential function late in endoplasmic reticulum (ER) to Golgi transport, and the redundant Ypt31/Ypt32 GTPases have been proposed to act in transport through and/or from the Golgi. Here we report that mutant alleles of YPT31 and YPT32, whose gene products have a reduced affinity for GTP, are able to suppress the dominant lethal phenotype of YPT1(N121I). Co-expression of YPT1(N121I) and the suppressor YPT31(N126I) allow essentially undisturbed secretory transport in the absence of the respective wild-type GTPases. Such mutant cells massively overaccumulate 60-100 nm vesicles and are heat sensitive. It appears likely that the mutant GTPases, which are defective in nucleotide binding, compete for the binding of common interacting protein(s). These and other genetic interactions between YPT1, YPT31/32, ARF1 and SEC4 described here strongly support the view that Ypt31p and Ypt32p have a central, Golgi-associated function in anterograde or retrograde transport.

Biological Transport↗