Displaying publications 141 - 160 of 270 in total

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  1. Guo J, Wu X, Too CL, Yin F, Lu X, He J, et al.
    PLoS One, 2012;7(7):e41228.
    PMID: 22829930 DOI: 10.1371/journal.pone.0041228
    OBJECTIVES: Dendritic cell immunoreceptor (DCIR) has been implicated in development of autoimmune disorders in rodent and DCIR polymorphisms were associated with anti-citrullinated proteins antibodies (ACPA)-negative rheumatoid arthritis (RA) in Swedish Caucasians. This study was undertaken to further investigate whether DCIR polymorphisms are also risk factors for the development of RA in four Asian populations originated from China and Malaysia.

    METHODS: We genotyped two DCIR SNPs rs2377422 and rs10840759 in Han Chinese population (1,193 cases, 1,278 controls), to assess their association with RA. Subsequently, rs2377422 was further genotyped in three independent cohorts of Malaysian-Chinese subjects (MY_Chinese, 254 cases, 206 controls), Malay subjects (MY_ Malay, 515 cases, 986 controls), and Malaysian-Indian subjects (MY_Indian, 378 cases, 285 controls), to seek confirmation of association in various ethnic groups. Meta-analysis was preformed to evaluate the contribution of rs2377422 polymorphisms to the development of ACPA-negative RA in distinct ethnic groups. Finally, we carried out association analysis of rs2377422 polymorphisms with DCIR mRNA expression levels.

    RESULTS: DCIR rs2377422 was found to be significantly associated with ACPA -negative RA in Han Chinese (OR 1.92, 95% CI 1.27-2.90, P=0.0020). Meta-analysis confirms DCIR rs2377422 as a risk factor for ACPA-negative RA across distinct ethnic groups (OR(overall) =1.17, 95% CI 1.06-1.30, P=0.003). The SNP rs2377422 polymorphism showed significant association with DCIR mRNA expression level, i.e. RA-risk CC genotype exhibit a significant increase in the expression of DCIR (P=0.0023, Kruskal-Wallis).

    CONCLUSIONS: Our data provide evidence for association between DCIR rs2377422 and RA in non-Caucasian populations and confirm the influence of DCIR polymorphisms on RA susceptibility, especially on ACPA-negative RA.
  2. Ramli AN, Mahadi NM, Shamsir MS, Rabu A, Joyce-Tan KH, Murad AM, et al.
    J Comput Aided Mol Des, 2012 Aug;26(8):947-61.
    PMID: 22710891 DOI: 10.1007/s10822-012-9585-7
    The structure of psychrophilic chitinase (CHI II) from Glaciozyma antarctica PI12 has yet to be studied in detail. Due to its low sequence identity (<30 %), the structural prediction of CHI II is a challenge. A 3D model of CHI II was built by first using a threading approach to search for a suitable template and to generate an optimum target-template alignment, followed by model building using MODELLER9v7. Analysis of the catalytic insertion domain structure in CHI II revealed an increase in the number of aromatic residues and longer loops compared to mesophilic and thermophilic chitinases. A molecular dynamics simulation was used to examine the stability of the CHI II structure at 273, 288 and 300 K. Structural analysis of the substrate-binding cleft revealed a few exposed aromatic residues. Substitutions of certain amino acids in the surface and loop regions of CHI II conferred an increased flexibility to the enzyme, allowing for an adaptation to cold temperatures. A substrate binding comparison of CHI II with the mesophilic chitinase from Coccidioides immitis, 1D2K, suggested that the psychrophilic adaptation and catalytic activity at low temperatures were achieved through a reduction in the number of salt bridges, fewer hydrogen bonds and an increase in the exposure of the hydrophobic side chains to the solvent.
  3. Yahya A, Bengtsson C, Lai TC, Larsson PT, Mustafa AN, Abdullah NA, et al.
    Mod Rheumatol, 2012 Aug;22(4):524-31.
    PMID: 22006120 DOI: 10.1007/s10165-011-0544-2
    We investigated the association between cigarette smoking and the risk of developing rheumatoid arthritis (RA) in the Malaysian population. A total of 1,056 RA patients and 1,416 matched controls aged 18-70 years within a defined area of Peninsular Malaysia were evaluated in a case-control study between August 2005 and December 2009. A case was defined as a person with early diagnosed RA using the 1987 American College of Rheumatology criteria for RA. Controls were randomly selected matched for sex, age, and residential area. Cases and controls answered a questionnaire on a broad range of issues, including lifestyle factors and smoking habits wherein current and former smoking was classified as ever-smoking. The presence of anti-citrullinated peptide antibodies (ACPA) was determined for cases and controls. We found that ever-smokers had an increased risk of developing ACPA-positive RA [odds ratio (OR) = 4.1, 95% confidence interval (CI) 1.9-9.2] but not ACPA-negative RA (OR = 0.7, 95% CI 0.3-2.0), compared with never-smokers. A significant dose-response relationship between cumulative dose of smoking and risk of ACPA-positive RA was observed (<20 pack-years OR = 3.3, 95% CI 1.1-9.8; at least 20 pack-years OR = 5.2, 95% CI 1.6-17.6). Hence, smoking is associated with an increased risk of ACPA-positive RA in the Malaysian population, in which the genetic context is similar to several other Asian countries.
  4. Ismail NF, Hamdan S, Mahadi NM, Murad AM, Rabu A, Bakar FD, et al.
    Biotechnol Lett, 2011 May;33(5):999-1005.
    PMID: 21234789 DOI: 10.1007/s10529-011-0517-8
    L-Asparaginase II signal peptide was used for the secretion of recombinant cyclodextrin glucanotransferase (CGTase) into the periplasmic space of E. coli. Despite its predominant localisation in the periplasm, CGTase activity was also detected in the extracellular medium, followed by cell lysis. Five mutant signal peptides were constructed to improve the periplasmic levels of CGTase. N1R3 is a mutated signal peptide with the number of positively charged amino acid residues in the n-region increased to a net charge of +5. This mutant peptide produced a 1.7-fold enhancement of CGTase activity in the periplasm and significantly decreased cell lysis to 7.8% of the wild-type level. The formation of intracellular inclusion bodies was also reduced when this mutated signal peptide was used as judged by SDS-PAGE. Therefore, these results provide evidence of a cost-effective means of expression of recombinant proteins in E. coli.
  5. Gill HK, Kumar HC, Dhaliwal JS, Zabidi F, Sendut IH, Noah RM, et al.
    Asian Pac J Allergy Immunol, 2012 Dec;30(4):313-20.
    PMID: 23393912
    BACKGROUND: The most common autosomal form of Chronic Granulomatous Disease, p47-phox deficient CGD, generally features a GT (deltaGT) deletion in the GTGT sequence at the start of exon 2 on the NCF-1 gene. This consistency is due to the coexistence of and the recombination between 2 homologous pseudogenes (psi s) and NCF-1. The GTGT: deltaGT ratio mirrors the NCF-I: NCF-1 psi ratio and is 2:4 in normal individuals.
    OBJECTIVE: To determine the molecular basis of the Autosomal-CGD in a family with 2 children, a male and female, affected by the disease. The female patient suffered recurrent infection, retinitis pigmentosa and discoid lupus.
    METHODS: Chemiluminescence (CL) was used to study the respiratory burst, while genetic analysis was done by RT-PCR, PCR, deltaGT and the 20bp gene scans.
    RESULTS: The CL response of the patient was profoundly low. The patient's p47-phox band was absent in the RT-PCR for NADPH-oxidase component mRNAs. The deltaGT scan showed that the patient's GTGT: deltaGT ratio was 0:6, the parents' and the younger brother's was 1:5 and the younger sister's was 2:4. Examination of other NCF-1/ NCF-1 psi s differences showed that the father had a compound deltaGT allele ie. deltaGT-20bp, inherited by the patient, and that both parents had compound GTGT alleles with a single 30bp segment in intron 1.
    CONCLUSIONS: The patient was a classic, homozygous deltaGT p47-phox deficient CGD with one allele harbouring a compound deltaGT-20bp gene. The deltaGT and 20bp gene scans offer a relatively simple and efficient means of defining a p47-phox deficient CGD patient.
    Key words: Chronic Granulomatous Disease, Primary Immunodeficiency, NCF-1, p47-phox, NADPH-oxidas
  6. Woon JS, Mackeen MM, Sudin AH, Mahadi NM, Illias RM, Murad AM, et al.
    Biotechnol Lett, 2016 May;38(5):825-32.
    PMID: 26830095 DOI: 10.1007/s10529-016-2045-z
    To express and determine the hydrolytic activity of a cellobiohydrolase (TTCBH6B) from the thermophilic fungus Thielavia terrestris in Pichia pastoris.
  7. Bakhtiar MF, Too CL, Tang MM, Sulaiman S, Tan LK, Ahmad-Fauzi NA, et al.
    Clin Exp Allergy, 2019 04;49(4):537-540.
    PMID: 30693574 DOI: 10.1111/cea.13347
  8. Muhamad NA, Buang SN, Jaafar S, Jais R, Tan PS, Mustapha N, et al.
    BMC Public Health, 2018 Dec 22;18(1):1402.
    PMID: 30577816 DOI: 10.1186/s12889-018-6316-6
    BACKGROUND: In 2006, 4 years of planning was started by the Ministry of Health, Malaysia (MOH), to implement the HPV (human papillomavirus) vaccination programme. An inter-agency and multi-sectoral collaborations were developed for Malaysia's HPV school-based immunisation programme. It was approved for nationwide school base implementation for 13-year-old girls or first year secondary students in 2010. This paper examines how the various strategies used in the implementation over the last 7 years (2010-2016) that unique to Malaysia were successful in achieving optimal coverage of the target population.

    METHODS: Free vaccination was offered to school girls in secondary school (year seven) in Malaysia, which is usually at the age of 13 in the index year. All recipients of the HPV vaccine were identified through school enrolments obtained from education departments from each district in Malaysia. A total of 242,638 girls aged between 12 to 13 years studying in year seven were approached during the launch of the program in 2010. Approximately 230,000 girls in secondary schools were offered HPV vaccine per year by 646 school health teams throughout the country from 2010 to 2016.

    RESULTS: Parental consent for their daughters to receive HPV vaccination at school was very high at 96-98% per year of the programme. Of those who provided consent, over 99% received the first dose each year and 98-99% completed the course per year. Estimated population coverage for the full vaccine course, considering also those not in school, is estimated at 83 to 91% per year. Rates of adverse events reports following HPV vaccination were low at around 2 per 100,000 and the majority was injection site reactions.

    CONCLUSION: A multisectoral and integrated collaborative structure and process ensured that the Malaysia school-based HPV immunisation programme was successful and sustained through the programme design, planning, implementation and monitoring and evaluation. This is a critical factor contributing to the success and sustainability of the school-based HPV immunisation programme with very high coverage.

  9. Low DE, Nurul-Aain AF, Tan WC, Tang JJ, Bakhtiar MF, Murad S, et al.
    Pharmacogenet Genomics, 2020 09;30(7):153-160.
    PMID: 32433341 DOI: 10.1097/FPC.0000000000000408
    OBJECTIVE: The association between human leukocyte antigen (HLA)-B*58:01 and risk of allopurinol-induced severe cutaneous adverse reactions (AIS) was observed across different populations. We explore the association between HLA-B*58:01 and AIS risk in multiethnic Malaysian population. The HLA-B*58:01 risk for different AIS clinical phenotypes and ethnicity was determined.

    METHODS: We performed a case-control association study by genotyping the HLA-B alleles of 55 patients with AIS [11 toxic epidermal necrolysis (TEN), 21 Steven Johnson syndrome (SJS) 22 drug reaction wit eosinophilia and systemic symptoms (DRESS) and one acute generalized exanthematous pustulosis (AGEP)] and 42 allopurinol-tolerant controls (ATC).

    RESULTS: HLA-B*58:01 was positive in 89.1 and 14.3% of the AIS and ATC study groups [odds ratio (OR) = 49.0, 95% confidence interval (CI) = 14.6-164.4, P < 0.0001)], respectively. Our data showed that 93.8% of the AIS-SJS/TEN patients and 86.4% of the AIS-DRESS patients were HLA-B*58:01 positive (AIS-SJS/TEN, OR = 90, 95% CI = 16.9-470.1, P < 0.0001 and AIS-DRESS OR = 38, 95% CI = 8.5-169.2, P < 0.0001). Stratification by ethnicity and clinical phenotypes revealed a significant increased risk between HLA-B*58:01 and Chinese-AIS patients (OR = 137.5, 95% CI = 11.3-1680.2, P < 0.0001), in particular Chinese patients with AIS-SJS/TEN phenotype (100% HLA-B*58:01 positive). HLA-B*58:01 was positive in 90.9% Chinese AIS-DRESS (P < 0.0001). Highly significant associations of HLA-B*58:01 were observed in Malay AIS-SJS/TEN (OR = 78, 95% CI = 9.8-619.9, P < 0.0001) and Malay AIS-DRESS (OR = 54, 95% CI = 6.6-442.9, P < 0.0001). Although the number of Indian-AIS patients was relatively small (n = 2), both were HLA-B*58:01 positive.

    CONCLUSION: Our data suggest strong associations between HLA-B*58:01 and AIS in Malaysian population with Chinese and Malays ethnicity. The strong association was also observed in three different clinical phenotypes of AIS, mainly the AIS-SJS/TEN.

  10. Abd Rahman NH, Jaafar NR, Abdul Murad AM, Abu Bakar FD, Shamsul Annuar NA, Md Illias R
    Int J Biol Macromol, 2020 Sep 15;159:577-589.
    PMID: 32380107 DOI: 10.1016/j.ijbiomac.2020.04.262
    Short-chain fructooligosaccharides (scFOSs) can be produced from the levan hydrolysis using levanase. Levanase from Bacillus lehensis G1 (rlevblg1) is an enzyme that specifically converts levan to scFOSs. However, the use of free levanase presents a lack of stability and reusability, thus hindering the synthesis of scFOSs for continuous reactions. Here, CLEAs for rlevblg1 were prepared and characterized. Cross-linked levanase aggregates using glutaraldehyde (CLLAs-ga) and bovine albumin serum (CLLAs-ga-bsa) showed the best activity recovery of 92.8% and 121.2%, respectively. The optimum temperature of CLLAs-ga and CLLAs-ga-bsa was increased to 35 °C and 40 °C, respectively, from its free rlevblg1 (30 °C). At high temperature (50 °C), the half-life of CLLAs-ga-bsa was higher than that of free rlevblg1 and CLLAs-ga. Both CLLAs exhibited higher stability at pH 9 and pH 10. Hyperactivation of CLLAs-ga-bsa was achieved with an effectiveness factor of more than 1 and with improved catalytic efficiency. After 3 h reaction, CLLAs-ga-bsa produced the highest total scFOSs yield of 35.4% and total sugar of 60.4% per gram levan. Finally, the reusability of CLLAs for 8 cycles with more than 50% activity retained makes them as a potential synthetic catalyst to be explored for scFOSs synthesis.
  11. Low KO, Mahadi NM, Rahim RA, Rabu A, Abu Bakar FD, Murad AM, et al.
    J Ind Microbiol Biotechnol, 2011 Sep;38(9):1587-97.
    PMID: 21336875 DOI: 10.1007/s10295-011-0949-0
    Direct transport of recombinant protein from cytosol to extracellular medium offers great advantages, such as high specific activity and a simple purification step. This work presents an investigation on the potential of an ABC (ATP-binding cassette) transporter system, the hemolysin transport system, for efficient protein secretion in Escherichia coli (E. coli). A higher secretory production of recombinant cyclodextrin glucanotransferase (CGTase) was achieved by a new plasmid design and subsequently by optimization of culture conditions via central composite design. An improvement of at least fourfold extracellular recombinant CGTase was obtained using the new plasmid design. The optimization process consisted of 20 experiments involving six star points and six replicates at the central point. The predicted optimum culture conditions for maximum recombinant CGTase secretion were found to be 25.76 μM IPTG, 1.0% (w/v) arabinose and 34.7°C post-induction temperature, with a predicted extracellular CGTase activity of 68.76 U/ml. Validation of the model gave an extracellular CGTase activity of 69.15 ± 0.71 U/ml, resulting in a 3.45-fold increase compared to the initial conditions. This corresponded to an extracellular CGTase yield of about 0.58 mg/l. We showed that a synergistic balance of transported protein and secretory pathway is important for efficient protein transport. In addition, we also demonstrated the first successful removal of the C-terminal secretion signal from the transported fusion protein by thrombin proteolytic cleavage.
  12. Hamsan MH, Nofal MM, Aziz SB, Brza MA, Dannoun EMA, Murad AR, et al.
    Polymers (Basel), 2021 Apr 11;13(8).
    PMID: 33920346 DOI: 10.3390/polym13081233
    Chitosan (CS)-dextran (DN) biopolymer electrolytes doped with ammonium iodide (NH4I) and plasticized with glycerol (GL), then dispersed with Zn(II)-metal complex were fabricated for energy device application. The CS:DN:NH4I:Zn(II)-complex was plasticized with various amounts of GL and the impact of used metal complex and GL on the properties of the formed electrolyte were investigated.The electrochemical impedance spectroscopy (EIS) measurements have shown that the highest conductivity for the plasticized system was 3.44 × 10-4 S/cm. From the x-ray diffraction (XRD) measurements, the plasticized electrolyte with minimum degree of crystallinity has shown the maximum conductivity. The effect of (GL) plasticizer on the film morphology was studied using FESEM. It has been confirmed via transference number analysis (TNM) that the transport mechanism in the prepared electrolyte is predominantly ionic in nature with a high transference number of ion (ti)of 0.983. From a linear sweep voltammetry (LSV) study, the electrolyte was found to be electrochemically constant as the voltage sweeps linearly up to 1.25 V. The cyclic voltammetry (CV) curve covered most of the area of the current-potential plot with no redox peaks and the sweep rate was found to be affecting the capacitance. The electric double-layer capacitor (EDLC) has shown a great performance of specific capacitance (108.3 F/g), ESR(47.8 ohm), energy density (12.2 W/kg) and power density (1743.4 W/kg) for complete 100 cycles at a current density of 0.5 mA cm-2.
  13. Too CL, Murad S, Hansson M, Alm LM, Dhaliwal JS, Holmdahl R, et al.
    Arthritis Rheumatol, 2017 01;69(1):58-69.
    PMID: 27483449 DOI: 10.1002/art.39827
    OBJECTIVE: Antibodies to the citrullinated protein antigens (ACPAs) are important in the diagnosis and pathogenesis of rheumatoid arthritis (RA). However, the prevalence of ACPAs with different fine specificities in different populations is unclear. This study sought to examine the fine specificity of the antibody responses toward citrullinated proteins in RA patients from Malaysia, an area where genetic and environmental determinants of RA are different from those in more frequently studied cohorts of Caucasian subjects.

    METHODS: A multiplex analytic microarray system was used to analyze the occurrence of antibodies to 10 different citrullinated peptides (filaggrin [fil307-324], vimentin [Vim2-17, Vim60-75], fibrinogen [Fibα563-583, Fibα580-600, Fibβ36-52, Fibβ62-81a, Fibβ62-81b], enolase [Eno5-21], and type II collagen [CitCII355-378]) in serum samples from 4,089 RA patients (1,231 Malaysian and 2,858 Swedish) and 827 healthy control subjects (249 Malaysian and 578 Swedish). The positive reaction threshold for each peptide was set separately for each population based on a specificity of 98%.

    RESULTS: Distinct differences in the frequencies of 5 ACPA fine specificities (Vim60-75, Vim2-17, Fibβ62-81b, Eno5-21, and CitCII355-378) were found between the Malaysian and Swedish RA populations, despite a nearly identical percentage of patients in each population who were positive for anti-cyclic citrullinated peptide 2 antibodies. In Malaysian RA patients compared with Swedish RA patients, the frequencies of antibodies to Vim60-75 (54% versus 44%, corrected P [Pcorr ] = 1.06 × 10-8 ) and CitCII355-378 (17% versus 13%, Pcorr  = 0.02) were significantly higher, while the frequencies of antibodies to Vim2-17 (25% versus 32%, Pcorr  = 1.91 × 10-4 ), Fibβ62-81b (15% versus 30%, Pcorr  = 2.47 × 10-22 ), and Eno5-21 (23% versus 50%, Pcorr  = 3.64 × 10-57 ) were significantly lower.

    CONCLUSION: Serum ACPA fine specificities differ between RA patients in different populations, although the total proportions of individuals positive for ACPAs are similar. Differing patterns of ACPA fine specificity could be attributed to variations in genetic and/or environmental factors.

  14. Abdul Murad NA, Othman Z, Khalid M, Abdul Razak Z, Hussain R, Nadesan S, et al.
    Dig Dis Sci, 2012 Nov;57(11):2863-72.
    PMID: 22669205 DOI: 10.1007/s10620-012-2240-2
    BACKGROUND: Colorectal cancer (CRC) is the third most common cancer worldwide with approximately 1 million cases diagnosed annually. In Malaysia, CRC is the second most common cancer in women and ranked first in men. The underlying cause of CRC remains unknown.

    AIMS: The aim of this study was to analyze the mutations in genes involved in CRC including MLH1, MSH2, KRAS, and APC genes.

    METHODS: A total of 76 patients were recruited. We used the polymerase chain reaction-denaturing high-performance liquid chromatography for the detection of mutations in the mismatch repair (MMR) and APC genes and the PCR single-strand conformation polymorphism for screening of the KRAS gene mutations.

    RESULTS: We identified 17 types of missense mutations in 38 out of 76 patients in our patients. Nine mutations were identified in the APC gene, five mutations were detected in the KRAS gene, and two mutations were identified in the MSH2 gene. Only one mutation was identified in MLH1. Out of these 17 mutations, eight mutations (47 %) were predicted to be pathogenic. Seven patients were identified with multiple mutations (3: MSH2 and KRAS, 1: KRAS and APC, 1: MLH1 and APC, 2: APC and APC).

    CONCLUSIONS: We have established the PCR-DHPLC and PCR-SSCP for screening of mutations in CRC patients. This study has given a snapshot of the spectrum of mutations in the four genes that were analyzed. Mutation screening in patients and their family members will help in the early detection of CRC and hence will reduce mortality due to CRC.

  15. Che Mat MF, Abdul Murad NA, Ibrahim K, Mohd Mokhtar N, Wan Ngah WZ, Harun R, et al.
    Int J Oncol, 2016 Dec;49(6):2359-2366.
    PMID: 27840905 DOI: 10.3892/ijo.2016.3755
    Glioblastoma multiforme (GBM) is an aggressive brain tumor and most patients have poor prognosis. Despite many advances in research, there has been no significant improvement in the patient survival rate. New molecular therapies are being studied and RNA interference (RNAi) therapy is one of the promising approaches to improve prognosis and increase survival in patients with GBM. We performed a meta‑analysis of five different microarray datasets and identified 460 significantly upregulated genes in GBM. Loss‑of‑function screening of these upregulated genes using LN18 cells was performed to identify the significant target genes for glioma. Further investigations were performed using siRNA in LN18 cells and various functional assays were carried out on the selected candidate gene to understand further its role in GBM. We identified PROS1 as a candidate gene for GBM from the meta‑analysis and RNAi screening. Knockdown of PROS1 in LN18 cells significantly induced apoptosis compared to siPROS1‑untreated cells (p<0.05). Migration in cells treated with siPROS1 was reduced significantly (p<0.05) and this was confirmed with wound-healing assay. PROS1 knockdown showed substantial reduction in cell invasion up to 82% (p<0.01). In addition, inhibition of PROS1 leads to decrease in cellular proliferation by 18%. Knockdown of PROS1 in LN18 cells caused activation of both of the extrinsic and intrinsic apoptotic pathways. It caused major upregulation of FasL which is important for death receptor signaling activation and also downregulation of GAS6 and other members of TAM family of receptors. PROS1 may play an important role in the development of GBM through cellular proliferation, migration and invasion as well as apoptosis. Targeting PROS1 in GBM could be a novel therapeutic strategy in GBM treatment.
  16. Ling JG, Mansor MH, Abdul Murad AM, Mohd Khalid R, Quay DHX, Winkler M, et al.
    J Biotechnol, 2020 Jan 10;307:55-62.
    PMID: 31545972 DOI: 10.1016/j.jbiotec.2019.09.008
    Carboxylic acid reductases (CARs) are attracting burgeoning attention as biocatalysts for organic synthesis of aldehydes and their follow-up products from economic carboxylic acid precursors. The CAR enzyme class as a whole, however, is still poorly understood. To date, relatively few CAR sequences have been reported, especially from fungal sources. Here, we sought to increase the diversity of the CAR enzyme class. Six new CAR sequences from the white-rot fungus Pycnoporus cinnabarinus were identified from genome-wide mining. Genome and gene clustering analysis suggests that these PcCAR enzymes play different natural roles in Basidiomycete systems, compared to their type II Ascomycete counterparts. The cDNA sequences of all six Pccar genes were deduced and analysis of their corresponding amino acid sequence showed that they encode for proteins of similar properties that possess a conserved modular functional tri-domain arrangement. Phylogenetic analyses showed that all PcCAR enzymes cluster together with the other type IV CARs. One candidate, PcCAR4, was cloned and over-expressed recombinantly in Escherichia coli. Subsequent biotransformation-based screening with a panel of structurally-diverse carboxylic acid substrates suggest that PcCAR4 possessed a more pronounced substrate specificity compared to previously reported CARs, preferring to reduce sterically-rigid carboxylic acids such as benzoic acid. These findings thus present a new functionally-distinct member of the CAR enzyme class.
  17. Seman WM, Bakar SA, Bukhari NA, Gaspar SM, Othman R, Nathan S, et al.
    J Biotechnol, 2014 Aug 20;184:219-28.
    PMID: 24910973 DOI: 10.1016/j.jbiotec.2014.05.034
    A Pichia pastoris transformant carrying the cutinase cDNA of Glomerella cingulata was over-expressed in a 5L bioreactor (2.0L working volume) under fed-batch conditions. Bioreactor experiments rely on varying selected parameters in repeated rounds of optimisation: here these included duration of induction, pH and temperature. Highest cell densities (320gL(-1) wet cell weight) with a cutinase production of 3800mgL(-1) and an activity of 434UmL(-1) were achieved 24h after induction with methanol in basal salt medium (at pH 5 and 28°C). Characterisation of the cutinase showed that it was stable between pH 6 and pH 11, had an optimum pH of 8.0 and retained activity for 30min at 50°C (optimum temperature 25°C).The preferred substrates of G. cingulata cutinase were the medium- to long-chain ρ-nitrophenyl esters of ρ-nitrophenylcaprylate (C8), ρ-nitrophenyllaurate (C12) and ρ-nitrophenylmyristate (C14), with the highest catalytic efficiency, kcat/Km of 7.7±0.7mM(-1)s(-1) for ρ-nitrophenylcaprylate. Microscopic analyses showed that the G. cingulata cutinase was also capable of depolymerising the high molecular weight synthetic polyester, polyethylene terephthalate.
  18. Low KO, Mahadi NM, Abdul Rahim R, Rabu A, Abu Bakar FD, Abdul Murad AM, et al.
    J Biotechnol, 2010 Dec;150(4):453-9.
    PMID: 20959127 DOI: 10.1016/j.jbiotec.2010.10.001
    The hemolysin transport system was found to mediate the release of cyclodextrin glucanotransferase (CGTase) into the extracellular medium when it was fused to the C-terminal 61 amino acids of HlyA (HlyAs(61)). To produce an improved-secretion variant, the hly components (hlyAs, hlyB and hlyD) were engineered by directed evolution using error-prone PCR. Hly mutants were screened on solid LB-starch plate for halo zone larger than the parent strain. Through screening of about 1 × 10(4) Escherichia coli BL21(DE3) transformants, we succeeded in isolating five mutants that showed a 35-217% increase in the secretion level of CGTase-HlyAs(61) relative to the wild-type strain. The mutation sites of each mutant were located at HlyB, primarily along the transmembrane domain, implying that the corresponding region was important for the improved secretion of the target protein. In this study we describe the finding of novel site(s) of HlyB responsible for enhancing secretion of CGTase in E. coli.
  19. Jaafar NR, Khoiri NM, Ismail NF, Mahmood NAN, Abdul Murad AM, Abu Bakar FD, et al.
    Enzyme Microb Technol, 2020 Oct;140:109625.
    PMID: 32912685 DOI: 10.1016/j.enzmictec.2020.109625
    Endo-β-1,3-glucanase from alkalophilic bacterium, Bacillus lehensis G1 (Blg32) composed of 284 amino acids with a predicted molecular mass of 31.6 kDa is expressed in Escherichia coli and purified to homogeneity. Herein, Blg32 characteristics, substrates and product specificity as well as structural traits that might be involved in the production of sugar molecules are analysed. This enzyme functions optimally at the temperature of 70 °C, pH value of 8.0 with its catalytic activity strongly enhanced by Mn2+. Remarkably, the purified enzyme is highly stable in high temperature and alkaline conditions. It exhibits the highest activity on laminarin (376.73 U/mg) followed by curdlan and yeast β-glucan. Blg32 activity increased by 62% towards soluble substrate (laminarin) compared to insoluble substrate (curdlan). Hydrolytic products of laminarin were oligosaccharides with degree of polymerisation (DP) of 1 to 5 with the main product being laminaritriose (DP3). This suggests that the active site of Blg32 could recognise up to five glucose units. High concentration of Blg32 mainly produces glucose whilst low concentration of Blg32 yields oligosaccharides with different DP (predominantly DP3). A theoretical structural model of Blg32 was constructed and structural analysis revealed that Trp156 is involved in multiple hydrophobic stacking interactions. The amino acid was predicted to participate in substrate recognition and binding. It was also exhibited that catalytic groove of Blg32 has a narrow angle, thus limiting the substrate binding reaction. All these properties and knowledge of the subsites are suggested to be related to the possible mode of action of how Blg32 produces glucooligosaccharides.
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