Displaying publications 1 - 20 of 92 in total

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  1. Recent Advances in Overexpression of Functional Recombinant Lipases
    Alias FL, Nezhad NG, Normi YM, Ali MSM, Budiman C, Leow TC
    Mol Biotechnol, 2023 Nov;65(11):1737-1749.
    PMID: 36971996 DOI: 10.1007/s12033-023-00725-y
    Heterologous functional expression of the recombinant lipases is typically a bottleneck due to the expression in the insoluble fraction as inclusion bodies (IBs) which are in inactive form. Due to the importance of lipases in various industrial applications, many investigations have been conducted to discover suitable approaches to obtain functional lipase or increase the expressed yield in the soluble fraction. The utilization of the appropriate prokaryotic and eukaryotic expression systems, along with the suitable vectors, promoters, and tags, has been recognized as a practical approach. One of the most powerful strategies to produce bioactive lipases is using the molecular chaperones co-expressed along with the target protein's genes into the expression host to produce the lipase in soluble fraction as a bioactive form. The refolding of expressed lipase from IBs (inactive) is another practical strategy which is usually carried out through chemical and physical methods. Based on recent investigations, the current review simultaneously highlights strategies to express the bioactive lipases and recover the bioactive lipases from the IBs in insoluble form.
    Matched MeSH terms: Recombinant Proteins/chemistry
  2. Fulltext Ion-Pair Interaction and Hydrogen Bonds as Main Features of Protein Thermostability in Mutated T1 Recombinant Lipase Originating from Geobacillus zalihae
    Ishak SNH, Kamarudin NHA, Ali MSM, Leow ATC, Rahman RNZRA
    Molecules, 2020 Jul 28;25(15).
    PMID: 32731607 DOI: 10.3390/molecules25153430
    A comparative structure analysis between space- and an Earth-grown T1 recombinant lipase from Geobacillus zalihae had shown changes in the formation of hydrogen bonds and ion-pair interactions. Using the space-grown T1 lipase validated structure having incorporated said interactions, the recombinant T1 lipase was re-engineered to determine the changes brought by these interactions to the structure and stability of lipase. To understand the effects of mutation on T1 recombinant lipase, five mutants were developed from the structure of space-grown T1 lipase and biochemically characterized. The results demonstrate an increase in melting temperature up to 77.4 °C and 76.0 °C in E226D and D43E, respectively. Moreover, the mutated lipases D43E and E226D had additional hydrogen bonds and ion-pair interactions in their structures due to the improvement of stability, as observed in a longer half-life and an increased melting temperature. The biophysical study revealed differences in β-Sheet percentage between less stable (T118N) and other mutants. As a conclusion, the comparative analysis of the tertiary structure and specific residues associated with ion-pair interactions and hydrogen bonds could be significant in revealing the thermostability of an enzyme with industrial importance.
    Matched MeSH terms: Recombinant Proteins/chemistry
  3. Fulltext A review of machine learning methods to predict the solubility of overexpressed recombinant proteins in Escherichia coli
    Habibi N, Mohd Hashim SZ, Norouzi A, Samian MR
    BMC Bioinformatics, 2014;15:134.
    PMID: 24885721 DOI: 10.1186/1471-2105-15-134
    Over the last 20 years in biotechnology, the production of recombinant proteins has been a crucial bioprocess in both biopharmaceutical and research arena in terms of human health, scientific impact and economic volume. Although logical strategies of genetic engineering have been established, protein overexpression is still an art. In particular, heterologous expression is often hindered by low level of production and frequent fail due to opaque reasons. The problem is accentuated because there is no generic solution available to enhance heterologous overexpression. For a given protein, the extent of its solubility can indicate the quality of its function. Over 30% of synthesized proteins are not soluble. In certain experimental circumstances, including temperature, expression host, etc., protein solubility is a feature eventually defined by its sequence. Until now, numerous methods based on machine learning are proposed to predict the solubility of protein merely from its amino acid sequence. In spite of the 20 years of research on the matter, no comprehensive review is available on the published methods.
    Matched MeSH terms: Recombinant Proteins/chemistry*
  4. Intensification of Inclusion Body Processing via Temperature-Based Refolding
    Wong RS, Alias NNM, Ong EBB, Liew MWO
    Methods Mol Biol, 2023;2617:189-200.
    PMID: 36656525 DOI: 10.1007/978-1-0716-2930-7_13
    Inclusion bodies (IB) are dense insoluble aggregates of mostly misfolded polypeptides that usually result from recombinant protein overexpression. IB formation has been observed in protein expression systems such as E. coli, yeast, and higher eukaryotes. To recover soluble recombinant proteins in their native state, IB are commonly first solubilized with a high concentration of denaturant. This is followed by concurrent denaturant removal or reduction and a transition into a refolding-favorable chemical environment to facilitate the refolding of solubilized protein to its native state. Due to the high concentration of denaturant used, conventional refolding approaches can result in dilute products and are buffer inefficient. To circumvent the limitations of conventional refolding approaches, a temperature-based refolding approach which combines a low concentration of denaturant (0.5 M guanidine hydrochloride, GdnHCl) with a high temperature (95 °C) during solubilization was proposed. In this chapter, we describe a temperature-based refolding approach for the recovery of core streptavidin (cSAV) from IB. Through the temperature-based approach, intensification was achieved through the elimination of a concentration step which would be required by a dilution approach and through a reduction in buffer volumes required for dilution or denaturant removal. High-temperature treatment during solubilization may have also resulted in the denaturation and aggregation of undesired host-cell proteins, which could then be removed through a centrifugation step resulting in refolded cSAV of high purity without the need for column purification. Refolded cSAV was characterized by biotin-binding assay and SDS-PAGE, while purity was determined by RP-HPLC.
    Matched MeSH terms: Recombinant Proteins/chemistry
  5. Expression of soluble human Neonatal Fc-receptor (FcRn) in Escherichia coli through modification of growth environment
    Ng WK, Lim TS, Lai NS
    Protein Expr Purif, 2016 11;127:73-80.
    PMID: 27412717 DOI: 10.1016/j.pep.2016.07.004
    Neonatal Fc-receptor (FcRn) with its affinity to immunoglobulin G (IgG) has been the subject of many pharmacokinetic studies in the past century. This protein is well known for its unique feature in maintaining the circulating IgG from degradation in blood plasma. FcRn is formed by non-covalent association between the α-chain with the β-2-microglobulin (β2m). Many studies have been conducted to produce FcRn in the laboratory, mainly using mammalian tissue culture as host for recombinant protein expression. In this study, we demonstrate a novel strategy to express the α-chain of FcRn using Escherichia coli as the expression host. The expression vector that carries the cDNA of the α-chain was transformed into expression host, Rosetta-gami 2 strain for inducible expression. The bacterial culture was grown in a modified growth medium which constitutes of terrific broth, sodium chloride (NaCl), glucose and betaine. A brief heat shock at 45 °C was carried out after induction, before the temperature for expression was reduced to 22 °C and grown for 16 h. The soluble form of the α-chain of FcRn expressed was tested in the ELISA and dot blot immunoassay to confirm its native functionality. The results implied that the α-chain of FcRn expressed using this method is functional and retains its pH-dependent affinity to IgG. Our study significantly suggests that the activity of human FcRn remain active and functional in the absence of β2m.
    Matched MeSH terms: Recombinant Proteins/chemistry
  6. Functional characterisation of cellobiohydrolase I (Cbh1) from Trichoderma virens UKM1 expressed in Aspergillus niger
    Wahab AFFA, Abdul Karim NA, Ling JG, Hasan NS, Yong HY, Bharudin I, et al.
    Protein Expr Purif, 2019 02;154:52-61.
    PMID: 30261309 DOI: 10.1016/j.pep.2018.09.014
    Cellobiohydrolases catalyze the processive hydrolysis of cellulose into cellobiose. Here, a Trichoderma virens cDNA predicted to encode for cellobiohydrolase (cbhI) was cloned and expressed heterologously in Aspergillus niger. The cbhI gene has an open reading frame of 1518 bp, encoding for a putative protein of 505 amino acid residues with a calculated molecular mass of approximately 54 kDa. The predicted CbhI amino acid sequence has a fungal type carbohydrate binding module separated from a catalytic domain by a threonine rich linker region and showed high sequence homology with glycoside hydrolase family 7 proteins. The partially purified enzyme has an optimum pH of 4.0 with stability ranging from pH 3.0 to 6.0 and an optimum temperature of 60 °C. The partially purified CbhI has a specific activity of 4.195 Umg-1 and a low Km value of 1.88 mM when p-nitrophenyl-β-D-cellobioside (pNPC) is used as the substrate. The catalytic efficiency (kcat/Km) was 5.68 × 10-4 mM-1s-1, which is comparable to the CbhI enzymes from Trichoderma viridae and Phanaerochaete chrysosporium. CbhI also showed activity towards complex substrates such as Avicel (0.011 Umg-1), which could be useful in complex biomass degradation. Interestingly, CbhI also exhibited a relatively high inhibition constant (Ki) for cellobiose with a value of 8.65 mM, making this enzyme more resistant to end-product inhibition compared to other fungal cellobiohydrolases.
    Matched MeSH terms: Recombinant Proteins/chemistry
  7. Fulltext Recombinant dense granular protein (GRA5) for detection of human toxoplasmosis by Western blot
    Ching XT, Lau YL, Fong MY, Nissapatorn V, Andiappan H
    Biomed Res Int, 2014;2014:690529.
    PMID: 24987700 DOI: 10.1155/2014/690529
    Toxoplasma gondii infects all warm-blooded animals, including humans, causing serious public health problems and great economic loss for the food industry. Commonly used serological tests require costly and hazardous preparation of whole Toxoplasma lysate antigens from tachyzoites. Here, we have evaluated an alternative method for antigen production, which involved a prokaryotic expression system. Specifically, we expressed T. gondii dense granular protein-5 (GRA5) in Escherichia coli and isolated it by affinity purification. The serodiagnostic potential of the purified recombinant GRA5 (rGRA5) was tested through Western blot analysis against 212 human patient serum samples. We found that rGRA5 protein was 100% specific for analysis of toxoplasmosis-negative human sera. Also, rGRA5 was able to detect acute and chronic T. gondii infections (sensitivities of 46.8% and 61.2%, resp.).
    Matched MeSH terms: Recombinant Proteins/chemistry
  8. Fulltext Evaluation of the effects of Mitragyna speciosa alkaloid extract on cytochrome P450 enzymes using a high throughput assay
    Kong WM, Chik Z, Ramachandra M, Subramaniam U, Aziddin RE, Mohamed Z
    Molecules, 2011 Aug 29;16(9):7344-56.
    PMID: 21876481 DOI: 10.3390/molecules16097344
    The extract from Mitragyna speciosa has been widely used as an opium substitute, mainly due to its morphine-like pharmacological effects. This study investigated the effects of M. speciosa alkaloid extract (MSE) on human recombinant cytochrome P450 (CYP) enzyme activities using a modified Crespi method. As compared with the liquid chromatography-mass spectrometry method, this method has shown to be a fast and cost-effective way to perform CYP inhibition studies. The results indicated that MSE has the most potent inhibitory effect on CYP3A4 and CYP2D6, with apparent half-maximal inhibitory concentration (IC(50)) values of 0.78 µg/mL and 0.636 µg/mL, respectively. In addition, moderate inhibition was observed for CYP1A2, with an IC(50) of 39 µg/mL, and weak inhibition was detected for CYP2C19. The IC(50) of CYP2C19 could not be determined, however, because inhibition was <50%. Competitive inhibition was found for the MSE-treated CYP2D6 inhibition assay, whereas non-competitive inhibition was shown in inhibition assays using CYP3A4, CYP1A2 and CYP2C19. Quinidine (CYP2D6), ketoconazole (CYP3A4), tranylcypromine (CYP2C19) and furafylline (CYP1A2) were ACCESSused as positive controls throughout the experiments. This study shows that MSE may contribute to an herb-drug interaction if administered concomitantly with drugs that are substrates for CYP3A4, CYP2D6 and CYP1A2.
    Matched MeSH terms: Recombinant Proteins/chemistry
  9. Mapping of domains responsible for nucleocapsid protein-phosphoprotein interaction of Henipaviruses
    Chan YP, Koh CL, Lam SK, Wang LF
    J Gen Virol, 2004 Jun;85(Pt 6):1675-1684.
    PMID: 15166452 DOI: 10.1099/vir.0.19752-0
    Hendra virus (HeV) and Nipah virus (NiV) are members of a new genus, Henipavirus, in the family paramyxoviridae. Each virus encodes a phosphoprotein (P) that is significantly larger than its counterparts in other known paramyxoviruses. The interaction of this unusually large P with its nucleocapsid protein (N) was investigated in this study by using recombinant full-length and truncated proteins expressed in bacteria and a modified protein-blotting protein-overlay assay. Results from our group demonstrated that the N and P of both viruses were able to form not only homologous, but also heterologous, N-P complexes, i.e. HeV N was able to interact with NiV P and vice versa. Deletion analysis of the N and P revealed that there were at least two independent N-binding sites on P and they resided at the N and C termini, respectively. Similarly, more than one P-binding site was present on N and one of these was mapped to a 29 amino acid (aa) C-terminal region, which on its own was sufficient to interact with the extreme C-terminal 165 aa region of P.
    Matched MeSH terms: Recombinant Proteins/chemistry
  10. Fulltext Effective refolding of a cysteine rich glycoside hydrolase family 19 recombinant chitinase from Streptomyces griseus by reverse dilution and affinity chromatography
    Oyeleye AO, Mohd Yusoff SF, Abd Rahim IN, Leow ATC, Saidi NB, Normi YM
    PLoS One, 2020;15(10):e0241074.
    PMID: 33091044 DOI: 10.1371/journal.pone.0241074
    Conventional refolding methods are associated with low yields due to misfolding and high aggregation rates or very dilute proteins. In this study, we describe the optimization of the conventional methods of reverse dilution and affinity chromatography for obtaining high yields of a cysteine rich recombinant glycoside hydrolase family 19 chitinase from Streptomyces griseus HUT6037 (SgChiC). SgChiC is a potential biocontrol agent and a reference enzyme in the study and development of chitinases for various applications. The overexpression of SgChiC was previously achieved by periplasmic localization from where it was extracted by osmotic shock and then purified by hydroxyapatite column chromatography. In the present study, the successful refolding and recovery of recombinant SgChiC (r-SgChiC) from inclusion bodies (IB) by reverse dilution and column chromatography methods is respectively described. Approximately 8 mg of r-SgChiC was obtained from each method with specific activities of 28 and 52 U/mg respectively. These yields are comparable to that obtained from a 1 L culture volume of the same protein isolated from the periplasmic space of E. coli BL21 (DE3) as described in previous studies. The higher yields obtained are attributed to the successful suppression of aggregation by a stepwise reduction of denaturant from high, to intermediate, and finally to low concentrations. These methods are straight forward, requiring the use of fewer refolding agents compared with previously described refolding methods. They can be applied to the refolding of other cysteine rich proteins expressed as inclusion bodies to obtain high yields of actively folded proteins. This is the first report on the recovery of actively folded SgChiC from inclusion bodies.
    Matched MeSH terms: Recombinant Proteins/chemistry
  11. Development of a rapid and improved two-dimensional electrophoresis method for the separation of protein lysate
    Kwan SH, Ismail MN
    Biomed Chromatogr, 2019 Dec;33(12):e4686.
    PMID: 31452214 DOI: 10.1002/bmc.4686
    Researchers frequently use two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) prior to mass spectrometric analysis in a proteomics approach. The i2D-PAGE method, which 'inverts' the dimension of protein separation of the conventional 2D-PAGE, is presented in this publication. Protein lysate of Channa striata, a freshwater snakehead fish, was separated based on its molecular weight in the first dimension and its isoelectric point in the second dimension. The first-dimension separation was conducted on a gel-free separation device, and the protein mixture was fractionated into 12 fractions in chronological order of increasing molecular weight. The second-dimension separation featured isoelectric focusing, which further separated the proteins within the same fraction according to their respective isoelectric point. Advantages of i2D-PAGE include better visualisation of the isolated protein, easy identification on protein isoforms, shorter running time, customisability and reproducibility. Erythropoietin standard was applied to i2D-PAGE to show its effectiveness for separating protein isoforms. Various staining methods such as Coomassie blue staining and silver staining are also applicable to i2D-PAGE. Overall, the i2D-PAGE separation method effectively separates protein lysate and is suitable for application in proteomics research.
    Matched MeSH terms: Recombinant Proteins/chemistry
  12. Process intensification of core streptavidin production through high-cell-density cultivation of recombinant E. coli and a temperature-based refolding method
    Chua LH, Tan SC, Liew MWO
    J Biotechnol, 2018 Jun 20;276-277:34-41.
    PMID: 29679607 DOI: 10.1016/j.jbiotec.2018.04.012
    An intensified process was developed that enables high level production of recombinant core streptavidin (cSAV), a non-glycosylated tetrameric protein utilised in a wide range of applications. A pH-stat fed-batch feeding strategy was employed to achieve high-cell-density and improve volumetric yield of cSAV which was expressed as inclusion bodies (IBs). The effect of induction at different cell densities (OD 20, 60 and 100) on volumetric and specific yield were then studied. Highest volumetric yield of cSAV (1550 mg L-1) was obtained from induction at OD 100 without significant reductions in specific yield. To recover active cSAV from IBs, the possibility of refolding using a temperature-based refolding method was investigated. Refolded cSAV obtained from temperature-based refolding were then compared against cSAV refolded with conventional dialysis and dilution methods using quantitative and qualitative metrics. The temperature-based refolding method was found to improve the yield of cSAV by 6-18% in comparison to conventional methods without compromising quality. Intensification was achieved by reductions in process volumes and a more concentrated product stream. Using the newly developed process, the volumetric yield of cSAV IBs was improved by thirty-six fold in comparison to low-cell-density shake flask cultivation, and 33% of cSAV can be recovered from IBs at 90% purity.
    Matched MeSH terms: Recombinant Proteins/chemistry
  13. Fulltext Optimization of physical conditions for the production of thermostable T1 lipase in Pichia guilliermondii strain SO using response surface methodology
    Abu ML, Nooh HM, Oslan SN, Salleh AB
    BMC Biotechnol, 2017 Nov 10;17(1):78.
    PMID: 29126403 DOI: 10.1186/s12896-017-0397-7
    BACKGROUND: Pichia guilliermondii was found capable of expressing the recombinant thermostable lipase without methanol under the control of methanol dependent alcohol oxidase 1 promoter (AOXp 1). In this study, statistical approaches were employed for the screening and optimisation of physical conditions for T1 lipase production in P. guilliermondii.

    RESULT: The screening of six physical conditions by Plackett-Burman Design has identified pH, inoculum size and incubation time as exerting significant effects on lipase production. These three conditions were further optimised using, Box-Behnken Design of Response Surface Methodology, which predicted an optimum medium comprising pH 6, 24 h incubation time and 2% inoculum size. T1 lipase activity of 2.0 U/mL was produced with a biomass of OD600 23.0.

    CONCLUSION: The process of using RSM for optimisation yielded a 3-fold increase of T1 lipase over medium before optimisation. Therefore, this result has proven that T1 lipase can be produced at a higher yield in P. guilliermondii.

    Matched MeSH terms: Recombinant Proteins/chemistry
  14. Biophysical characterization of a recombinant lipase KV1 from Acinetobacter haemolyticus in relation to pH and temperature
    Batumalaie K, Khalili E, Mahat NA, Huyop F, Wahab RA
    Biochimie, 2018 Sep;152:198-210.
    PMID: 30036604 DOI: 10.1016/j.biochi.2018.07.011
    Spectroscopic and calorimetric methods were employed to assess the stability and the folding aspect of a novel recombinant alkaline-stable lipase KV1 from Acinetobacter haemolyticus under varying pH and temperature. Data on far ultraviolet-circular dichroism of recombinant lipase KV1 under two alkaline conditions (pH 8.0 and 12.0) at 40 °C reveal strong negative ellipticities at 208, 217, 222 nm, implying its secondary structure belonging to a α + β class with 47.3 and 39.0% ellipticity, respectively. Results demonstrate that lipase KV1 adopts its most stable conformation at pH 8.0 and 40 °C. Conversely, the protein assumes a random coil structure at pH 4.0 and 80 °C, evident from a strong negative peak at ∼ 200 nm. This blue shift suggests a general decline in enzyme activity in conjunction with the partially or fully unfolded state that invariably exposed more hydrophobic surfaces of the lipase protein. The maximum emission at ∼335 nm for pH 8.0 and 40 °C indicates the adoption of a favorable protein conformation with a high number of buried tryptophan residues, reducing solvent exposure. Appearance of an intense Amide I absorption band at pH 8.0 corroborates an intact secondary structure. A lower enthalpy value for pH 4.0 over pH 8.0 and 12.0 in the differential scanning calorimetric data corroborates the stability of the lipase at alkaline conditions, while a low Km (0.68 ± 0.03 mM) for tributyrin verifies the high affinity of lipase KV1 for the substrate. The data, herein offer useful insights into future structure-based tunable catalytic activity of lipase KV1.
    Matched MeSH terms: Recombinant Proteins/chemistry
  15. Strategies for humanizing glycosylation pathways and producing recombinant glycoproteins in microbial expression systems
    Khan AH, Noordin R
    Biotechnol Prog, 2019 03;35(2):e2752.
    PMID: 30457225 DOI: 10.1002/btpr.2752
    Homogeneously glycosylated proteins are essential for analyzing the structure of N-glycans, studying their consequences inside cells, and developing therapeutic glycoproteins. However, the isolation of glycoproteins with homogeneous glycans from human is difficult since glycoforms slightly differ from each other with respect to molecular weight and charge. Microbial expression systems have numerous benefits in expression technology and have gained great attention, because they are more adaptable to the biotechnology industry. While selecting an expression host, the glycosylation pattern must be taken into account, because glycosylation strongly depends on cellular production system and selected production clone. This review discussed the technological developments in glycoengineering of microbial expression systems for humanizing the glycosylation profile and highlighted the expression potential of Leishmania expression system. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2752, 2019.
    Matched MeSH terms: Recombinant Proteins/chemistry
  16. Fulltext Recombinant Production and Characterization of an Extracellular Subtilisin-Like Serine Protease from Acinetobacter baumannii of Fermented Food Origin
    Muhammed NS, Hussin N, Lim AS, Jonet MA, Mohamad SE, Jamaluddin H
    Protein J, 2021 06;40(3):419-435.
    PMID: 33870461 DOI: 10.1007/s10930-021-09986-5
    Acinetobacter baumannii is a ubiquitous bacteria that is increasingly becoming a formidable nosocomial pathogen. Due to its clinical relevance, studies on the bacteria's secretory molecules especially extracellular proteases are of interest primarily in relation to the enzyme's role in virulence. Besides, favorable properties that extracellular proteases possess may be exploited for commercial use thus there is a need to investigate extracellular proteases from Acinetobacter baumannii to gain insights into their catalytic properties. In this study, an extracellular subtilisin-like serine protease from Acinetobacter baumannii designated as SPSFQ that was isolated from fermented food was recombinantly expressed and characterized. The mature catalytically active form of SPSFQ shared a high percentage sequence identity of 99% to extracellular proteases from clinical isolates of Acinetobacter baumannii and Klebsiella pneumoniae as well as a moderately high percentage identity to other bacterial proteases with known keratinolytic and collagenolytic activity. The homology model of mature SPSFQ revealed its structure is composed of 10 β-strands, 8 α-helices, and connecting loops resembling a typical architecture of subtilisin-like α/β motif. SPSFQ is catalytically active at an optimum temperature of 40 °C and pH 9. Its activity is stimulated in the presence of Ca2+ and severely inhibited in the presence of PMSF. SPSFQ also displayed the ability to degrade several tissue-associated protein substrates such as keratin, collagen, and fibrin. Accordingly, our study shed light on the catalytic properties of a previously uncharacterized extracellular serine protease from Acinetobacter baumannii that warrants further investigations into its potential role as a virulence factor in pathogenicity and commercial applications.
    Matched MeSH terms: Recombinant Proteins/chemistry
  17. Recombinant production of Epstein-Barr virus BZLF1 trans-activator and characterization of its DNA-binding specificity
    Lim CS, Goh SL, Krishnan G, Ng CC
    Protein Expr Purif, 2014 Mar;95:8-12.
    PMID: 24291446 DOI: 10.1016/j.pep.2013.11.007
    This paper describes the recombinant production of a biologically active Epstein-Barr virus BZLF1 trans-activator, i.e., Z-encoded broadly reactive activator (ZEBRA), that recognized specific DNA motifs. We used auto-induction for histidine-tagged BZLF1 expression in Escherichia coli and immobilized cobalt affinity membrane chromatography for protein purification under native conditions. We obtained the purified BZLF1 at a yield of 5.4mg per gram of wet weight cells at 75% purity, in which 27% of the recombinant BZLF1 remained biologically active. The recombinant BZLF1 bound to oligonucleotides containing ZEBRA response elements, either AP-1 or ZIIIB, but not a ZIIIB mutant. The recombinant BZLF1 showed a specific DNA-binding activity which could be useful for functional studies.
    Matched MeSH terms: Recombinant Proteins/chemistry*
  18. Production of refolded Toxoplasma gondii recombinant SAG1-related sequence 3 (SRS3) and its use for serodiagnosis of human toxoplasmosis
    Mirzadeh A, Saadatnia G, Golkar M, Babaie J, Noordin R
    Protein Expr Purif, 2017 05;133:66-74.
    PMID: 28263855 DOI: 10.1016/j.pep.2017.03.001
    SAG1-related sequence 3 (SRS3) is one of the major Toxoplasma gondii tachyzoite surface antigens and has been shown to be potentially useful for the detection of toxoplasmosis. This protein is highly conformational due to the presence of six disulfide bonds. To achieve solubility and antigenicity, SRS3 depends on proper disulfide bond formation. The aim of this study was to over-express the SRS3 protein with correct folding for use in serodiagnosis of the disease. To achieve this, a truncated SRS3 fusion protein (rtSRS3) was produced, containing six histidyl residues at both terminals and purified by immobilized metal affinity chromatography. The refolding process was performed through three methods, namely dialysis in the presence of chemical additives along with reduced/oxidized glutathione and drop-wise dilution methods with reduced/oxidized glutathione or reduced DTT/oxidized glutathione. Ellman's assay and ELISA showed that the protein folding obtained by the dialysis method was the most favorable, probably due to the correct folding. Subsequently, serum samples from individuals with chronic infection (n = 76), probable acute infection (n = 14), and healthy controls (n = 81) were used to determine the usefulness of the refolded rtSRS3 for Toxoplasma serodiagnosis. The results of the developed IgG-ELISA showed a diagnostic specificity of 91% and a sensitivity of 82.89% and 100% for chronic and acute serum samples, respectively. In conclusion, correctly folded rtSRS3 has the potential to be used as a soluble antigen for the detection of human toxoplasmosis.
    Matched MeSH terms: Recombinant Proteins/chemistry
  19. Expression of stable and active human DNA topoisomerase I in Pichia pastoris
    Chan MK, Lim SK, Miswan N, Chew AL, Noordin R, Khoo BY
    Protein Expr Purif, 2018 Jan;141:52-62.
    PMID: 28893606 DOI: 10.1016/j.pep.2017.09.003
    This study described the isolation of the coding region of human topoisomerase I (TopoI) from MDA-MB-231 and the expression of multiple copy recombinant genes in four Pichia pastoris strains. First, polymerase chain reaction (PCR)-amplification of the enzyme coding region was performed. The PCR fragment was cloned into pPICZ-α-A vector and sequenced. It was then transformed into X33, GS115, SMD1168H and KM71H strains of Pichia. PCR-screening for positive clones was performed, and estimation of multiple copy integrants in each Pichia strain was carried out using agar plates containing increasing concentrations of Zeocin(®). The selected clones of multiple copy recombinant genes were then induced for TopoI expression in shaker flasks. GS115 and SMD1168 were found to be better Pichia strains to accommodate the recombinant gene for the expression of TopoI extracellularly. However, the DNA relaxation activity revealed that only the target enzyme in the culture supernatants of GS115-pPICZ-α-A-TopoI exhibited consistent enzyme activity over the cultivation time-points. Active enzyme activity was inhibited by Camptothecin. The enzyme produced can be used for in-house gel-based DNA relaxation assay development in performing high throughput screening for target-specific growth inhibitors that display similar effect as the TopoI inhibitors. These inhibitors may contribute to the improvement of the treatment of cancer patients.
    Matched MeSH terms: Recombinant Proteins/chemistry
  20. Fulltext Structural modeling and biochemical characterization of recombinant KPN_02809, a zinc-dependent metalloprotease from Klebsiella pneumoniae MGH 78578
    Wong MT, Choi SB, Kuan CS, Chua SL, Chang CH, Normi YM, et al.
    Int J Mol Sci, 2012;13(1):901-17.
    PMID: 22312293 DOI: 10.3390/ijms13010901
    Klebsiella pneumoniae is a Gram-negative, cylindrical rod shaped opportunistic pathogen that is found in the environment as well as existing as a normal flora in mammalian mucosal surfaces such as the mouth, skin, and intestines. Clinically it is the most important member of the family of Enterobacteriaceae that causes neonatal sepsis and nosocomial infections. In this work, a combination of protein sequence analysis, structural modeling and molecular docking simulation approaches were employed to provide an understanding of the possible functions and characteristics of a hypothetical protein (KPN_02809) from K. pneumoniae MGH 78578. The computational analyses showed that this protein was a metalloprotease with zinc binding motif, HEXXH. To verify this result, a ypfJ gene which encodes for this hypothetical protein was cloned from K. pneumoniae MGH 78578 and the protein was overexpressed in Escherichia coli BL21 (DE3). The purified protein was about 32 kDa and showed maximum protease activity at 30 °C and pH 8.0. The enzyme activity was inhibited by metalloprotease inhibitors such as EDTA, 1,10-phenanthroline and reducing agent, 1,4-dithiothreitol (DTT). Each molecule of KPN_02809 protein was also shown to bind one zinc ion. Hence, for the first time, we experimentally confirmed that KPN_02809 is an active enzyme with zinc metalloprotease activity.
    Matched MeSH terms: Recombinant Proteins/chemistry
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