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Search Results: 1 - 10 of 12567 matches for " Joo Shun Tan "
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Pullulanase: Role in Starch Hydrolysis and Potential Industrial Applications
Siew Ling Hii,Joo Shun Tan,Tau Chuan Ling,Arbakariya Bin Ariff
Enzyme Research , 2012, DOI: 10.1155/2012/921362
Abstract: The use of pullulanase (EC 3.2.1.41) has recently been the subject of increased applications in starch-based industries especially those aimed for glucose production. Pullulanase, an important debranching enzyme, has been widely utilised to hydrolyse the α-1,6 glucosidic linkages in starch, amylopectin, pullulan, and related oligosaccharides, which enables a complete and efficient conversion of the branched polysaccharides into small fermentable sugars during saccharification process. The industrial manufacturing of glucose involves two successive enzymatic steps: liquefaction, carried out after gelatinisation by the action of α-amylase; saccharification, which results in further transformation of maltodextrins into glucose. During saccharification process, pullulanase has been used to increase the final glucose concentration with reduced amount of glucoamylase. Therefore, the reversion reaction that involves resynthesis of saccharides from glucose molecules is prevented. To date, five groups of pullulanase enzymes have been reported, that is, (i) pullulanase type I, (ii) amylopullulanase, (iii) neopullulanase, (iv) isopullulanase, and (v) pullulan hydrolase type III. The current paper extensively reviews each category of pullulanase, properties of pullulanase, merits of applying pullulanase during starch bioprocessing, current genetic engineering works related to pullulanase genes, and possible industrial applications of pullulanase. 1. Introduction Starch is a major industrial raw material and is chemically and/or enzymatically processed into variety of products for subsequent use in various industries, ranging from food (especially high-fructose and glucose syrups) to washing detergent industries [1–3]. Starch is, after cellulose, one of the most abundant heterogeneous polysaccharide produced by plants in the form of water insoluble granules. It is a polymeric carbohydrate, composed of C, H, and O atoms in the ratio of 6?:?10?:?5, (C6H10O5)??. Molecules of starch are made of hundreds or thousands of glucose, corresponding to values of ?? that range from 50 to several thousands. Glucose units are linked to one another through C1 oxygen as glucosidic bond. Glucosidic bonds are stable under alkaline conditions while treatment of starch with acids or certain enzymes breaks the polymer into its constituent glucose molecules. The end unit of the polymeric chain has a latent aldehyde group and is known as the reducing end group. Most starches are mixture of two polymers with high molecular weight: (i) a linear chain molecule—amylose, and (ii) a branch
Isolation of Pediococcus acidilactici Kp10 with ability to secrete bacteriocin-like inhibitory substance from milk products for applications in food industry
Abbasiliasi Sahar,Tan Joo Shun,Ibrahim Tengku Azmi Tengku,Ramanan Ramakrishnan Nagasundara
BMC Microbiology , 2012, DOI: 10.1186/1471-2180-12-260
Abstract: Background Lactic acid bacteria (LAB) can be isolated from traditional milk products. LAB that secrete substances that inhibit pathogenic bacteria and are resistant to acid, bile, and pepsin but not vancomycin may have potential in food applications. Results LAB isolated from a range of traditional fermented products were screened for the production of bacteriocin-like inhibitory substances. A total of 222 LAB strains were isolated from fermented milk products in the form of fresh curds, dried curds, and ghara (a traditional flavor enhancer prepared from whey), and fermented cocoa bean. Eleven LAB isolates that produced antimicrobial substances were identified as Lactococcus lactis, Lactobacillus plantarum, and Pediococcus acidilactici strains by biochemical methods and 16S rDNA gene sequencing. Of these, the cell-free supernatant of Kp10 (P. acidilactici) most strongly inhibited Listeria monocytogenes. Further analysis identified the antimicrobial substance produced by Kp10 as proteinaceous in nature and active over a wide pH range. Kp10 (P. acidilactici) was found to be catalase-negative, able to produce β-galactosidase, resistant to bile salts (0.3%) and acidic conditions (pH 3), and susceptible to most antibiotics. Conclusion Traditionally prepared fermented milk products are good sources of LAB with characteristics suitable for industrial applications. The isolate Kp10 (P. acidilactici) shows potential for the production of probiotic and functional foods.
The Severe Acute Respiratory Syndrome (SARS)-coronavirus 3a protein may function as a modulator of the trafficking properties of the spike protein
Yee-Joo Tan
Virology Journal , 2005, DOI: 10.1186/1743-422x-2-5
Abstract: It has been shown that the severe acute respiratory syndrome-coronavirus genome contains open reading frames that encode for proteins with no homologue in other coronaviruses. One of them is the 3a protein, which is expressed during infection in vitro and in vivo. The 3a protein, which contains a tyrosine-dependent sorting signal in its cytoplasmic domain, is expressed on the cell surface and can undergo internalization. In addition, 3a can bind to the spike protein and through this interaction, it may be able to cause the spike protein to become internalized, resulting in a decrease in its surface expression.The effects of 3a on the internalization of cell surface spike protein can be examined biochemically and the significance of the interplay between these two viral proteins during viral infection can be studied using reverse genetics methodology.If this hypothesis is proven, it will indicate that the severe acute respiratory syndrome-coronavirus modulates the surface expression of the spike protein via a different mechanism from other coronaviruses. The interaction between 3a and S, which are expressed from separate subgenomic RNA, would be important for controlling the trafficking properties of S. The cell surface expression of S in infected cells significantly impacts viral assembly, viral spread and viral pathogenesis. Modulation by this unique pathway could confer certain advantages during the replication of the severe acute respiratory syndrome-coronavirus.The recent severe acute respiratory syndrome (SARS) epidemic, which affected over 30 countries, resulted in more than 8000 cases of infection and more than 800 fatalities (World Health Organization, http://www.who.int/csr/sars/country/en/ webcite). A novel coronavirus was identified as the aetiological agent of SARS [1]. Analysis of the nucleotide sequence of this novel SARS coronavirus (SARS-CoV) showed that the viral genome is nearly 30 kb in length and contains 14 potential open reading frames (ORFs) [
Genetic predictors of response to anti-tumor necrosis factor drugs in rheumatoid arthritis
Rachael Joo Lee Tan,Anne Barton
Rheumatology Reports , 2009, DOI: 10.4081/rr.2009.e1
Abstract: The introduction of anti-tumor necrosis factor (anti-TNF) agents has dramatically improved the outlook for many patients with rheumatoid arthritis (RA). However, 30% of patients fail to respond to treatment for unknown reasons. While research has identified clinical markers of response, including baseline disease activity, disability and the concurrent use of disease modifying therapy, these account for only a small proportion of the variation in treatment response. A number of groups, therefore, have started to investigate genetic markers of response to anti-TNF therapies. To date, many of these studies have been small, underpowered and have largely been restricted to the analysis of candidate genes. The only replicated and validated genetic predictor of anti-TNF response is the 308G>A SNP in the TNF promoter region, but the amount of variation in response accounted for by this marker is modest. It is unknown whether variation in treatment response is determined by several genes each with a small effect size or small numbers of genes with large effect sizes but what is certain is the need for a non-hypothesis driven approach in order to identify further genetic markers of anti-TNF response. The identification of genetic predictors of response to anti-TNF therapies would enable clinicians to tailor treatment of these expensive and potentially harmful agents to patients most likely to benefit from them.
A 3D Matching Method for Organic Training Samples Alignment Based on Surface Curvature Distribution  [PDF]
Guangxu Li, Hyoungseop Kim, Joo Kooi Tan, Seiji Ishikawa, Akiyoshi Yamamoto
Open Journal of Medical Imaging (OJMI) , 2011, DOI: 10.4236/ojmi.2011.12006
Abstract: The fundamental step to get a Statistical Shape Model (SSM) is to align all the training samples to the same spatial modality. In this paper, we propose a new 3D alignment method for organic training samples matching, whose modalities are orientable and surface figures could be recognized. It is a feature based alignment method which matches two models depending on the distribution of surface curvature. According to the affine transformation on 2D Gaussian map, the distances between the corresponding parts on surface could be minimized. We applied our proposed method on 5 cases left lung training samples alignment and 4 cases liver training samples alignment. The experiment results were performed on the left lung training samples and the liver training samples. The availability of proposed method was confirmed.
A new β-octamolybdate(VI) salt based on 1,4-bis(2-methyl-1H-imidazol-1-yl)butane
Shun-Li Li,Ke Tan
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808035022
Abstract: The title compound, bis[2,2′-dimethyl-3,3′-(butane-1,4-diyl)diimidazol-1-ium] β-octamolybdate(VI), (C12H20N4)2[Mo8O26], was produced by hydrothermal reaction of an acidified aqueous solution of Na2MoO4 and 1,4-bis(2-methyl-1H-imidazol-1-yl)butane (hereafter L). The structure of the title compound consists of the β-octamolybdate anions having a center of symmetry, and protonated [H2L]2+ cations, which link the β-octamolybdate anions, generating a supramolecular chain via hydrogen bonds.
1,4-Bis[2-(2-pyridyl)-1H-imidazol-1-yl]butane
Ke Tan,Shun-Li Li
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808036775
Abstract: The title compound, C20H20N6, was isolated from dimethyl sulfoxide solution using 2-(1H-imidazol-2-yl)pyridine and 1,4-dichlorobutane in the presence of NaOH.
A putative diacidic motif in the SARS-CoV ORF6 protein influences its subcellular localization and suppression of expression of co-transfected expression constructs
Vithiagaran Gunalan, Ali Mirazimi, Yee-Joo Tan
BMC Research Notes , 2011, DOI: 10.1186/1756-0500-4-446
Abstract: Using a transient transfection system, ORF6's ability to suppress the expression of co-transfected expression constructs was measured in a quantitative manner. While ORF6 does not have a global effect on protein synthesis, quantitative real-time PCR revealed that it down-regulated the mRNA level of the co-transfected myc-nsp8 gene. Furthermore, alanine substitution of a diacidic cluster motif (aa53-56) in the ORF6 gene caused a reduction in the suppression of expression of co-transfected myc-nsp8 gene. Our previous study revealed that ORF6 localized to vesicular structures in SARS-CoV infected Vero E6 cells. Here, ORF6 was observed to be localized to similar vesicular structures in Vero E6 cells which have been transiently transfected with a mammalian expression plasmid encoding for untagged ORF6. ORF6 showed partial colocalization with cellular proteins CD63 and Lamp1, suggesting that the vesicular structures may be a subpopulation of endosomal/lysosomal vesicles. The alanine substitution of the diacidic cluster motif also altered the subcellular localization of the ORF6 protein, indicating a potential relationship between the subcellular localization of the ORF6 protein and its ability to suppress the expression of co-transfected expression constructs.By combining quantitative real-time PCR and transient transfection system, a simple and safe method is established to measure ORF6's ability to suppress the expression of co-transfected myc-nsp8. In addition, immunofluorescence analysis revealed that the subcellular localization of ORF6 when expressed on its own is similar to that observed in SARS-CoV infected cells. Through the use of these two assays, a putative diacidic motif in the ORF6 protein was found to influence its subcellular localization and ability to suppress the expression of co-transfected expression constructs.An outbreak of Severe Acute Respiratory Syndrome (SARS) in 2003 which carried with it a fatality rate of 8% was traced to a novel coronavirus
Computational Epigenetics: the new scientific paradigm
Shen Jean Lim,Tin Wee Tan,Joo Chuan Tong
Bioinformation , 2010,
Abstract: Epigenetics has recently emerged as a critical field for studying how non-gene factors can influence the traits and functions of an organism. At the core of this new wave of research is the use of computational tools that play critical roles not only in directing the selection of key experiments, but also in formulating new testable hypotheses through detailed analysis of complex genomic information that is not achievable using traditional approaches alone. Epigenomics, which combines traditional genomics with computer science, mathematics, chemistry, biochemistry and proteomics for the large-scale analysis of heritable changes in phenotype, gene function or gene expression that are not dependent on gene sequence, offers new opportunities to further our understanding of transcriptional regulation, nuclear organization, development and disease. This article examines existing computational strategies for the study of epigenetic factors. The most important databases and bioinformatic tools in this rapidly growing field have been reviewed.
Prediction of desmoglein-3 peptides reveals multiple shared T-cell epitopes in HLA DR4- and DR6- associated Pemphigus vulgaris
Tong Joo,Tan Tin,Sinha Animesh A,Ranganathan Shoba
BMC Bioinformatics , 2006, DOI: 10.1186/1471-2105-7-s5-s7
Abstract: Background Pemphigus vulgaris (PV) is a severe autoimmune blistering skin disorder that is strongly associated with major histocompatibility complex class II alleles DRB1*0402 and DQB1*0503. The target antigen of PV, desmoglein 3 (Dsg3), is crucial for initiating T-cell response in early disease. Although a number of T-cell specificities within Dsg3 have been reported, the number is limited and the role of T-cells in the pathogenesis of PV remains poorly understood. We report here a structure-based model for the prediction of peptide binding to DRB1*0402 and DQB1*0503. The scoring functions were rigorously trained, tested and validated using experimentally verified peptide sequences. Results High predictivity is obtained for both DRB1*0402 (r2 = 0.90, s = 1.20 kJ/mol, q2 = 0.82, spress = 1.61 kJ/mol) and DQB1*0503 (r2 = 0.95, s = 1.20 kJ/mol, q2 = 0.75, spress = 2.15 kJ/mol) models, compared to experimental data. We investigated the binding patterns of Dsg3 peptides and illustrate the existence of multiple immunodominant epitopes that may be responsible for both disease initiation and propagation in PV. Further analysis reveals that DRB1*0402 and DQB1*0503 may share similar specificities by binding peptides at different binding registers, thus providing a molecular mechanism for the dual HLA association observed in PV. Conclusion Collectively, the results of this study provide interesting new insights into the pathology of PV. This is the first report illustrating high-level of cross-reactivity between both PV-implicated alleles, DRB1*0402 and DQB1*0503, as well as the existence of a potentially large number of T-cell epitopes throughout the entire Dsg3 extracellular domain (ECD) and transmembrane region. Our results reveal that DR4 and DR6 PV may initiate in the ECD and transmembrane region respectively, with implications for immunotherapeutic strategies for the treatment of this autoimmune disease.
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