Displaying publications 61 - 77 of 77 in total

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  1. Purification and characterization of new bio-plastic degrading enzyme from Burkholderia cepacia DP1
    Azura Azami N, Ira Aryani W, Aik-Hong T, Amirul AA
    Protein Expr Purif, 2019 03;155:35-42.
    PMID: 30352276 DOI: 10.1016/j.pep.2018.10.008
    Depolymerase is an enzyme that plays an important role in the hydrolysis of polyhydroxyalkanoates [PHAs]. In the current study, Burkholderia cepacia DP1 was obtained from Penang, Malaysia in which the enzyme was purified using ion exchange and gel filtration (Superdex-75) column chromatography. The molecular mass of the enzyme was estimated to be 53.3 kDa using SDS-PAGE. The enzyme activity was increased to 36.8 folds with the recovery of 16.3% after purification. The enzyme activity was detected between pH 6.0-10 and at 35-55 °C with pH 6.0 and 45 °C facilitating the maximum activity. Depolymerase was inactivated by Tween-20, Tween-80, SDS and PMSF, but insensitive to metal ions (Mg2+, Ca2+, K+, Na2+, Fe3+) and organic solvents (methanol, ethanol, and acetone). The apparent Km values of the purified P(3HB) depolymerase enzyme for P(3HB) and P(3HB-co-14%3HV) were 0.7 mg/ml and 0.8 mg/ml, respectively. The Vmax values of the purified enzyme were 10 mg/min and 8.89 mg/min for P(3HB) and P(3HB-co-14%3HV), respectively. The current study discovered a new extracellular poly(3-hydroxybutyrate) [P(3HB)] depolymerase enzyme from Burkholderia cepacia DP1 isolated and purified to homogeneity from the culture supernatant. To the best of our knowledge, this is the first report demonstrating the purification and biochemical characterization of P(3HB) depolymerase enzyme from genus Burkholderia.
    Matched MeSH terms: Chromatography, Ion Exchange
  2. Source contribution of PM₂.₅ at different locations on the Malaysian Peninsula
    Ee-Ling O, Mustaffa NI, Amil N, Khan MF, Latif MT
    Bull Environ Contam Toxicol, 2015 Apr;94(4):537-42.
    PMID: 25652682 DOI: 10.1007/s00128-015-1477-9
    This study determined the source contribution of PM2.5 (particulate matter <2.5 μm) in air at three locations on the Malaysian Peninsula. PM2.5 samples were collected using a high volume sampler equipped with quartz filters. Ion chromatography was used to determine the ionic composition of the samples and inductively coupled plasma mass spectrometry was used to determine the concentrations of heavy metals. Principal component analysis with multilinear regressions were used to identify the possible sources of PM2.5. The range of PM2.5 was between 10 ± 3 and 30 ± 7 µg m(-3). Sulfate (SO4 (2-)) was the major ionic compound detected and zinc was found to dominate the heavy metals. Source apportionment analysis revealed that motor vehicle and soil dust dominated the composition of PM2.5 in the urban area. Domestic waste combustion dominated in the suburban area, while biomass burning dominated in the rural area.
    Matched MeSH terms: Chromatography, Ion Exchange
  3. Identification of low abundance proteins in colorectal cancer tissues
    Lim SR, Gooi BH, Gam LH
    Cancer Biomark, 2012;12(4):185-98.
    PMID: 23568009 DOI: 10.3233/CBM-130307
    Detection of low abundance proteins always possesses challenges even with the currently available proteomics technologies.
    Matched MeSH terms: Chromatography, Ion Exchange
  4. Phytoestrogens levels determination in the cord blood from Malaysia rural and urban populations
    Mustafa AM, Malintan NT, Seelan S, Zhan Z, Mohamed Z, Hassan J, et al.
    Toxicol Appl Pharmacol, 2007 Jul 1;222(1):25-32.
    PMID: 17490695
    This study is a result of an analysis of free and conjugated phytoestrogens daidzein, genistein, daidzin, genistin and coumesterol in human cord blood plasma using LCMS. Cord blood was collected from urban and rural populations of Malaysia (n=300) to establish a simple preliminary database on the levels of the analyzed compounds in the collected samples. The study also aimed to look at the levels of phytoestrogens in babies during birth as this may have a profound effect on the developmental process. The sample clean up was carried out by solid-phase extraction using C18 column and passed through DEAE sephadex gel before analysis by LCMS. The mean concentrations of total phytoestrogens were daidzein (1.4+/-2.9 ng/ml), genistein (3.7+/-2.8 ng/ml), daidzin (3.5+/-3.1 ng/ml), genistin (19.5+/-4.2 ng/ml) and coumesterol (3.3+/-3.3 ng/ml). Distribution of phytoestrogen was found to be higher in samples collected from rural areas compared to that of urban areas.
    Matched MeSH terms: Chromatography, Ion Exchange
  5. Composition and source apportionment of surfactants in atmospheric aerosols of urban and semi-urban areas in Malaysia
    Wahid NB, Latif MT, Suratman S
    Chemosphere, 2013 Jun;91(11):1508-16.
    PMID: 23336924 DOI: 10.1016/j.chemosphere.2012.12.029
    This study was conducted to determine the composition and source apportionment of surfactant in atmospheric aerosols around urban and semi-urban areas in Malaysia based on ionic compositions. Colorimetric analysis was undertaken to determine the concentrations of anionic surfactants as Methylene Blue Active Substances (MBAS) and cationic surfactants as Disulphine Blue Active Substances (DBAS) using a UV spectrophotometer. Ionic compositions were determined using ion chromatography for cations (Na(+), NH4(+), K(+), Mg(2+), Ca(2+)) and anions (F(-), Cl(-), NO3(-), SO4(2-)). Principle component analysis (PCA) combined with multiple linear regression (MLR) were used to identify the source apportionment of MBAS and DBAS. Results indicated that the concentrations of surfactants at both sampling sites were dominated by MBAS rather than DBAS especially in fine mode aerosols during the southwest monsoon. Three main sources of surfactants were identified from PCA-MLR analysis for MBAS in fine mode samples particularly in Kuala Lumpur, dominated by motor vehicles, followed by soil/road dust and sea spray. Besides, for MBAS in coarse mode, biomass burning/sea spray were the dominant source followed by motor vehicles/road dust and building material.
    Matched MeSH terms: Chromatography, Ion Exchange
  6. The rubber elongation factor of rubber trees (Hevea brasiliensis) is the major allergen in latex
    Czuppon AB, Chen Z, Rennert S, Engelke T, Meyer HE, Heber M, et al.
    J Allergy Clin Immunol, 1993 Nov;92(5):690-7.
    PMID: 8227860
    BACKGROUND: Allergy to latex-containing articles is becoming more and more important because it can result in unexpected life-threatening anaphylactic reactions in sensitized individuals.

    METHODS: A protein of 58 kd with an isoelectric point of 8.45 was purified from raw latex and from latex gloves and identified as the major allergen, completely blocking specific IgE antibodies in the serum of latex-sensitized subjects. The allergen is a noncovalent homotetramer molecule, in which the 14.6 kd monomer was identified, by amino acid composition and sequence homologies of tryptic peptides, to be the rubber elongation factor found in natural latex of the Malaysian rubber tree.

    RESULTS: Competitive immunoinhibition tests showed that the starch powder covering the finished gloves is the airborne carrier of the allergen, resulting in bronchial asthma on inhalation. The purified allergen can induce allergic reactions in the nanogram range.

    CONCLUSION: The identification of the allergen (Hev b I) may help to eliminate it during the production of latex-based articles in the future.

    Matched MeSH terms: Chromatography, Ion Exchange
  7. Gold(III) recovery from aqueous solutions by raw and modified chitosan: A review
    Chang SH
    Carbohydr Polym, 2021 Mar 15;256:117423.
    PMID: 33483013 DOI: 10.1016/j.carbpol.2020.117423
    Chitosan, a prestigious versatile biopolymer, has recently received considerable attention as a promising biosorbent for recovering gold ions, mainly Au(III), from aqueous solutions, particularly in modified forms. Confirming the assertion, this paper provides an up-to-date overview of Au(III) recovery from aqueous solutions by raw (unmodified) and modified chitosan. A particular emphasis is placed on the raw chitosan and its synthesis from chitin, characteristics of raw chitosan and their effects on metal sorption, modifications of raw chitosan for Au(III) sorption, and characterization of raw chitosan before and after modifications for Au(III) sorption. Comparisons of the sorption (conditions, percentage, capacity, selectivity, isotherms, thermodynamics, kinetics, and mechanisms), desorption (agents and percentage), and reusable properties between raw and modified chitosan in Au(III) recovery from aqueous solutions are also outlined and discussed. The major challenges and future prospects towards the large-scale applications of modified chitosan in Au(III) recovery from aqueous solutions are also addressed.
    Matched MeSH terms: Chromatography, Ion Exchange
  8. Structural identification of haemoglobin F Kuala Lumpur: alpha2 gamma2 22(B4)Asp leads to Gly; 136 Ala
    Luan Eng LI, Wiltshire BG, Lehmann H
    Biochim. Biophys. Acta, 1973 Oct 18;322(2):224-30.
    PMID: 4765089
    Matched MeSH terms: Chromatography, Ion Exchange
  9. Isolation and Characterization of Lectin from the Artist's Conk Medicinal Mushroom, Ganoderma applanatum (Agaricomycetes), and Evaluation of Its Antiproliferative Activity in HT-29 Colon Cancer Cells
    Kumaran S, Pandurangan AK, Shenbhagaraman R, Esa NM
    Int J Med Mushrooms, 2017;19(8):675-684.
    PMID: 29199567 DOI: 10.1615/IntJMedMushrooms.2017021274
    The growth and lectin production of Ganoderma applanatum, a white rot fungus, was optimized in broth cultures. The fungus was found to have a higher growth rate and higher lectin activity when grown in a medium adjusted to pH 6.5 at 26°C under stationary conditions. Expression of lectin activity started in 5-day-old mycelial culture; maximum activity was expressed after the 15th day of incubation. Among the various carbon and nitrogen sources tested, the carbon source sucrose and the nitrogen source yeast extract support maximum growth and lectin production. Lectin from G. applanatum was purified by ammonium sulfate precipitation and ion exchange chromatography. The purified fraction revealed a single band with a molecular weight of 35.0 kDa. Moreover, carbohydrates such as mannitol, glucose, sucrose, maltose, mannose, galactose, sorbose, and fructose were found to inhibit the hemagglutinating activity of the lectin. The purified lectins from G. applanatum contain cytotoxic and proapoptotic activities against HT-29 colon adenocarcinoma cells.
    Matched MeSH terms: Chromatography, Ion Exchange
  10. Purification and properties of two forms of glucoamylase from Aspergillus niger
    Amirul AA, Khoo SL, Nazalan MN, Razip MS, Azizan MN
    Folia Microbiol (Praha), 1996;41(2):165-74.
    PMID: 9138312
    A. niger produced alpha-glucosidase, alpha-amylase and two forms of glucoamylase when grown in a liquid medium containing raw tapioca starch as the carbon source. The glucoamylases, which formed the dominant components of amylolytic activity manifested by the organism, were purified to homogeneity by ammonium sulfate precipitation, ion-exchange and two cycles of gel filtration chromatography. The purified enzymes, designated GA1 and GA2, a raw starch digesting glucoamylase, were found to have molar masses of 74 and 96 kDa and isoelectric points of 3.8 and 3.95, respectively. The enzymes were found to have pH optimum of 4.2 and 4.5 for GA1 and GA2, respectively, and were both stable in a pH range of 3.5-9.0. Both enzymes were thermophilic in nature with temperature optimum of 60 and 65 degrees C, respectively, and were stable for 1 h at temperatures of up to 60 degrees C. The kinetic parameters Km and V showed that with both enzymes the branched substrates, starch and amylopectin, were more efficiently hydrolyzed compared to amylose. GA2, the more active of the two glucoamylases produced, was approximately six to thirteen times more active towards raw starches compared to GA1.
    Matched MeSH terms: Chromatography, Ion Exchange
  11. Co-composting of acid waste bentonites and their effects on soil properties and crop biomass
    Soda W, Noble AD, Suzuki S, Simmons R, Sindhusen LA, Bhuthorndharaj S
    J Environ Qual, 2006 Oct 27;35(6):2293-301.
    PMID: 17071900
    Acid waste bentonite is a byproduct from vegetable oil bleaching that is acidic (pH < 3.0) and hydrophobic. These materials are currently disposed of in landfills and could potentially have a negative impact on the effective function of microbes that are intolerant of acidic conditions. A study was undertaken using three different sources of acid waste bentonites, namely soybean oil bentonite (SB), palm oil bentonite (PB), and rice bran oil bentonite (RB). These materials were co-composted with rice husk, rice husk ash, and chicken litter to eliminate their acid reactivity and hydrophobic nature. The organic carbon (OC) content, pH, exchangeable cations, and cation exchange capacity (CEC) of the acid-activated bentonites increased significantly after the co-composting phase. In addition, the hydrophobic nature of these materials as measured using the water drop penetration time (WDPT) decreased from >10 800 s to 16 to 80 s after composting. Furthermore, these composted materials showed positive impacts on soil physical attributes including specific surface area, bulk density, and available water content for crop growth. Highly significant increases in maize biomass (Zea mays L.) production over two consecutive cropping cycles was observed in treatments receiving co-composted bentonite. The study clearly demonstrates the potential for converting an environmentally hazardous material into a high-quality soil conditioner using readily available agricultural byproducts. It is envisaged that the application of these composted acid waste bentonites to degraded soils will increase productivity and on-farm income, thus contributing toward food security and poverty alleviation.
    Matched MeSH terms: Chromatography, Ion Exchange
  12. Fulltext Preparation and controlled-release studies of a protocatechuic acid-magnesium/aluminum-layered double hydroxide nanocomposite
    Barahuie F, Hussein MZ, Hussein-Al-Ali SH, Arulselvan P, Fakurazi S, Zainal Z
    Int J Nanomedicine, 2013;8:1975-87.
    PMID: 23737666 DOI: 10.2147/IJN.S42718
    In the study reported here, magnesium/aluminum (Mg/Al)-layered double hydroxide (LDH) was intercalated with an anticancer drug, protocatechuic acid, using ion-exchange and direct coprecipitation methods, with the resultant products labeled according to the method used to produce them: "PANE" (ie, protocatechuic acid-Mg/Al nanocomposite synthesized using the ion-exchange method) and "PAND" (ie, protocatechuic acid-Mg/Al nanocomposite synthesized using the direct method), respectively. Powder X-ray diffraction and Fourier transform infrared spectroscopy confirmed the intercalation of protocatechuic acid into the inter-galleries of Mg/Al-LDH. The protocatechuic acid between the interlayers of PANE and PAND was found to be a monolayer, with an angle from the z-axis of 8° for PANE and 15° for PAND. Thermogravimetric and differential thermogravimetric analysis results revealed that the thermal stability of protocatechuic acid was markedly enhanced upon intercalation. The loading of protocatechuic acid in PANE and PAND was estimated to be about 24.5% and 27.5% (w/w), respectively. The in vitro release study of protocatechuic acid from PANE and PAND in phosphate-buffered saline at pH 7.4, 5.3, and 4.8 revealed that the nanocomposites had a sustained release property. After 72 hours incubation of PANE and PAND with MCF-7 human breast cancer and HeLa human cervical cancer cell lines, it was found that the nanocomposites had suppressed the growth of these cancer cells, with a half maximal inhibitory concentration of 35.6 μg/mL for PANE and 36.0 μg/mL for PAND for MCF-7 cells, and 19.8 μg/mL for PANE and 30.3 μg/mL for PAND for HeLa cells. No half maximal inhibitory concentration for either nanocomposite was found for 3T3 cells.
    Matched MeSH terms: Ion Exchange
  13. Purification and comparison of intracellular proteinase A in Candida spp. isolates from Malaysian and Iranian patients and infected mice
    Amri Saroukolaei S, Pei Pei C, Shokri H, Asadi F
    J Mycol Med, 2012 Jun;22(2):149-59.
    PMID: 23518017 DOI: 10.1016/j.mycmed.2012.01.002
    To compare the specific intracellular proteinase A activity in clinical isolates of Candida species isolated from Iranian and Malaysian patients, the blood and kidneys of mice infected by Candida cells isolated from these human patients.
    Matched MeSH terms: Chromatography, Ion Exchange
  14. Biosorption of copper ions from dilute aqueous solutions on base treated rubber (Hevea brasiliensis) leaves powder: kinetics, isotherm, and biosorption mechanisms
    Wan Ngah WS, Hanafiah MA
    J Environ Sci (China), 2008;20(10):1168-76.
    PMID: 19143339
    The efficiency of sodium hydroxide treated rubber (Hevea brasiliensis) leaves powder (NHBL) for removing copper ions from aqueous solutions has been investigated. The effects of physicochemical parameters on biosorption capacities such as stirring speed, pH, biosorbent dose, initial concentrations of copper, and ionic strength were studied. The biosorption capacities of NHBL increased with increase in pH, stirring speed and copper concentration but decreased with increase in biosorbent dose and ionic strength. The isotherm study indicated that NHBL fitted well with Langmuir model compared to Freundlich and Dubinin-Radushkevich models. The maximum biosorption capacity determined from Langmuir isotherm was 14.97 mg/g at 27 degrees C. The kinetic study revealed that pseudosecond order model fitted well the kinetic data, while Boyd kinetic model indicated that film diffusion was the main rate determining step in biosorption process. Based on surface area analysis, NHBL has low surface area and categorized as macroporous. Fourier transform infrared (FT-IR) analyses revealed that hydroxyl, carboxyl, and amino are the main functional groups involved in the binding of copper ions. Complexation was one of the main mechanisms for the removal of copper ions as indicated by FT-IR spectra. Ion exchange was another possible mechanism since the ratio of adsorbed cations (Cu2+ and H+) to the released cations (Na+, Ca2+, and Mg2+) from NHBL was almost unity. Copper ions bound on NHBL were able to be desorbed at > 99% using 0.05 mol/L HCl, 0.01 mol/L HNO3, and 0.01 mol/L EDTA solutions.
    Matched MeSH terms: Ion Exchange
  15. Isolation and characterization of the thrombin-like enzyme from Cryptelytrops albolabris (white-lipped tree viper) venom
    Tan NH, Fung SY, Yap YH
    Comp Biochem Physiol B Biochem Mol Biol, 2012 Jan;161(1):79-85.
    PMID: 21983189 DOI: 10.1016/j.cbpb.2011.09.009
    A thrombin-like enzyme (termed albolabrase) was isolated in purified form from the venom of Cryptelytrops albolabris (white-lipped tree viper) using high performance anion ion exchange and gel filtration chromatography. The molecular mass of albolabrase was 33.7 kDa as determined by SDS-PAGE and 35.8 kDa as determined by Superose gel filtration chromatography. The N-terminal sequence was determined to be VVGGDECNINE which is homologous to many snake venom thrombin-like enzymes. Albolabrase exhibits both arginine ester hydrolase and arginine amidase activities and the enzyme is fastidious towards tripeptide chromogenic anilide substrates. The fibrinogen clotting activity was optimum at 3mg/mL bovine fibrinogen, and showed distinct species differences in the following decreasing order: bovine fibrinogen>dog fibrinogen≈human fibrinogen>goat fibrinogen. The enzyme failed to clot both rabbit and cat fibrinogens. Reversed-phase HPLC analysis on the breakdown products of fibrinogenolytic action of albolabrase indicated that the enzyme belongs to the AB class of snake venom thrombin-like enzyme. In the indirect ELISA, IgG anti-albolabrase reacted extensively with most crotalid venoms, except with Tropidolaemus wagleri and Calloselasma rhodostoma venoms. The double sandwich ELISA, however, showed that anti-albolabrase reacted strongly only with venoms from the Trimeresurus complex, and that the results support the proposed new taxonomy changes concerning the Trimeresurus complex.
    Matched MeSH terms: Chromatography, Ion Exchange
  16. The enzymatic activities and lethal toxins of Trimeresurus wagleri (speckled pit viper) venom
    Tan NH, Tan CS
    Toxicon, 1989;27(3):349-57.
    PMID: 2543103
    Trimeresurus wagleri (speckled pit viper) venom exhibited the usual set of enzyme activities occurring in pit viper venoms but the content of alkaline phosphomonoesterase was unusually high, whereas the proportions of protease and arginine ester hydrolase were very low. The venom also exhibited weak thrombin-like activity but did not exhibit hemorrhagic or anticoagulant activity. Analysis of the Sephadex G-200 gel filtration fractions of the venom indicated that the lethal fraction was a low mol.wt protein, and that fractions exhibiting phosphodiesterase, phosphomonoesterase, arginine ester hydrolase, thrombin-like enzyme, L-amino acid oxidase and phospholipase A activities were not lethal. Two lethal toxins, designated as wagleri toxins 1 and 2, were isolated from the venom using Sephadex G-50 gel filtration chromatography followed by SP-Sephadex C-25 ion exchange chromatography. The mol.wts of the two toxins were 8900 by gel filtration. The LD50 (i.v.) values in mice for wagleri toxins 1 and 2 are 0.17 microgram/g and 0.19 microgram/g, respectively.
    Matched MeSH terms: Chromatography, Ion Exchange
  17. Isolation and characterization of the thrombin-like enzyme from Cryptelytrops purpureomaculatus venom
    Tan NH
    Comp Biochem Physiol C Toxicol Pharmacol, 2010 Jan;151(1):131-6.
    PMID: 19770070 DOI: 10.1016/j.cbpc.2009.09.002
    A thrombin-like enzyme, purpurase, was purified from the Cryptelytrops purpureomaculatus (mangrove pit viper) venom using high performance ion-exchange and gel filtration chromatography. The purified sample (termed purpurase) yielded a homogeneous band in SDS-polyacrylamide gel electrophoresis with a molecular weight of 35,000. The N-terminal sequence of purpurase was determined to be VVGGDECNINDHRSLVRIF and is homologous to many other venom thrombin-like enzymes. Purpurase exhibits both arginine ester hydrolase and amidase activities. Kinetic studies using tripeptide chromogenic anilide substrates showed that purpurase is not fastidious towards its substrate. The clotting times of fibrinogen by purpurase were concentration dependent, with optimum clotting activity at 3mg fibronogen/mL. The clotting activity by purpurase was in the following decreasing order: cat fibrinogen>human fibrinogen>dog fibrinogen>goat fibrinogen>rabbit fibrinogen. Reversed-phase HPLC analysis of the products of action of purpurase on bovine fibrinogen showed that only fibrinopeptide A was released. Indirect ELISA studies showed that anti-purpurase cross-reacted strongly with venoms of most crotalid venoms, indicating the snake venom thrombin-like enzymes generally possess similar epitopes. In the more specific double-sandwich ELISA, however, anti-purpurase cross-reacted only with venoms of certain species of the Trimeresurus complex, and the results support the recent proposed taxonomy changes concerning the Trimeresurus complex.
    Matched MeSH terms: Chromatography, Ion Exchange
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