Displaying publications 41 - 60 of 228 in total

Abstract:
Sort:
  1. Toluene promotes lid 2 interfacial activation of cold active solvent tolerant lipase from Pseudomonas fluorescens strain AMS8
    Yaacob N, Mohamad Ali MS, Salleh AB, Rahman RNZRA, Leow ATC
    J Mol Graph Model, 2016 07;68:224-235.
    PMID: 27474867 DOI: 10.1016/j.jmgm.2016.07.003
    The utilization of cold active lipases in organic solvents proves an excellent approach for chiral synthesis and modification of fats and oil due to the inherent flexibility of lipases under low water conditions. In order to verify whether this lipase can function as a valuable synthetic catalyst, the mechanism concerning activation of the lid and interacting solvent residues in the presence of organic solvent must be well understood. A new alkaline cold-adapted lipase, AMS8, from Pseudomonas fluorescens was studied for its structural adaptation and flexibility prior to its exposure to non-polar, polar aprotic and protic solvents. Solvents such as ethanol, toluene, DMSO and 2-propanol showed to have good interactions with active sites. Asparagine (Asn) and tyrosine (Tyr) were key residues attracted to solvents because they could form hydrogen bonds. Unlike in other solvents, Phe-18, Tyr-236 and Tyr-318 were predicted to have aromatic-aromatic side-chain interactions with toluene. Non-polar solvent also was found to possess highest energy binding compared to polar solvents. Due to this circumstance, the interaction of toluene and AMS8 lipase was primarily based on hydrophobicity and molecular recognition. The molecular dynamic simulation showed that lid 2 (residues 148-167) was very flexible in toluene and Ca(2+). As a result, lid 2 moves away from the catalytic areas, leaving an opening for better substrate accessibility which promotes protein activation. Only a single lid (lid 2) showed the movement following interactions with toluene, although AMS8 lipase displayed double lids. The secondary conformation of AMS8 lipase that was affected by toluene observed a reduction of helical strands and increased coil structure. Overall, this work shows that cold active lipase, AMS8 exhibits distinguish interfacial activation and stability in the presence of polar and non-polar solvents.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  2. Synthesis and biological activity of oxadiazole and triazolothiadiazole derivatives as tyrosinase inhibitors
    Lam KW, Syahida A, Ul-Haq Z, Abdul Rahman MB, Lajis NH
    Bioorg Med Chem Lett, 2010 Jun 15;20(12):3755-9.
    PMID: 20493688 DOI: 10.1016/j.bmcl.2010.04.067
    A series of 16 oxadiazole and triazolothiadiazole derivatives were designed, synthesized and evaluated as mushroom tyrosinase inhibitors. Five derivatives were found to display high inhibition on the tyrosinase activity ranging from 0.87 to 1.49 microM. Compound 5 exhibited highest tyrosinase inhibitory activity with an IC(50) value of 0.87+/-0.16 microM. The in silico protein-ligand docking using AUTODOCK 4.1 was successfully performed on compound 5 with significant binding energy value of -5.58 kcal/mol. The docking results also showed that the tyrosinase inhibition might be due to the metal chelating effect by the presence of thione functionality in compounds 1-5. Further studies revealed that the presence of hydrophobic group such as cycloamine derivatives played a major role in the inhibition. Piperazine moiety in compound 5 appeared to be involved in an extensive hydrophobic contact and a 2.9A hydrogen bonding with residue Glu 182 in the active site.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  3. Hydrophobic protein in colorectal cancer in relation to tumor stages and grades
    Yeoh LC, Loh CK, Gooi BH, Singh M, Gam LH
    World J Gastroenterol, 2010 Jun 14;16(22):2754-63.
    PMID: 20533595
    AIM: To identify differentially expressed hydrophobic proteins in colorectal cancer.

    METHODS: Eighteen pairs of colorectal cancerous tissues in addition to tissues from normal mucosa were analysed. Hydrophobic proteins were extracted from the tissues, separated using 2-D gel electrophoresis and analysed using Liquid Chromatography Tandem Mass Spectrometry (LC/MS/MS). Statistical analysis of the proteins was carried out in order to determine the significance of each protein to colorectal cancer (CRC) and also their relation to CRC stages, grades and patients' gender.

    RESULTS: Thirteen differentially expressed proteins which were expressed abundantly in either cancerous or normal tissues were identified. A number of these proteins were found to relate strongly with a particular stage or grade of CRC. In addition, the association of these proteins with patient gender also appeared to be significant.

    CONCLUSION: Stomatin-like protein 2 was found to be a promising biomarker for CRC, especially in female patients. The differentially expressed proteins identified were associated with CRC and may act as drug target candidates.

    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  4. Facile modulation of enantioselectivity of thermophilic Geobacillus zalihae lipase by regulating hydrophobicity of its Q114 oxyanion
    Abdul Wahab R, Basri M, Raja Abdul Rahman RN, Salleh AB, Abdul Rahman MB, Leow TC
    Enzyme Microb Technol, 2016 Nov;93-94:174-181.
    PMID: 27702478 DOI: 10.1016/j.enzmictec.2016.08.020
    Site-directed mutagenesis of the oxyanion-containing amino acid Q114 in the recombinant thermophilic T1 lipase previously isolated from Geobacillus zalihae was performed to elucidate its role in the enzyme's enantioselectivity and reactivity. Substitution of Q114 with a hydrophobic methionine to yield mutant Q114M increased enantioselectivity (3.2-fold) and marginally improved reactivity (1.4-fold) of the lipase in catalysing esterification of ibuprofen with oleyl alcohol. The improved catalytic efficiency of Q114L was concomitant with reduced flexibility in the active site while the decreased enantioselectivity of Q114L could be directly attributed to diminished electrostatic repulsion of the substrate carboxylate ion that rendered partial loss in steric hindrance and thus enantioselectivity. The highest E-values for both Q114L (E-value 14.6) and Q114M (E-value 48.5) mutant lipases were attained at 50°C, after 12-16h, with a molar ratio of oleyl alcohol to ibuprofen of 1.5:1 and at 2.0% (w/v) enzyme load without addition of molecular sieves. Pertinently, site-directed mutagenesis on the Q114 oxyanion of T1 resulted in improved enantioselectivity and such approach may be applicable to other lipases of the same family. We demonstrated that electrostatic repulsion phenomena could affect flexibility/rigidity of the enzyme-substrate complex, aspects vital for enzyme activity and enantioselectivity of T1.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  5. Gelatine enhances drug dispersion in alginate bilayer film via the formation of crystalline microaggregates
    Thu HE, Ng SF
    Int J Pharm, 2013 Sep 15;454(1):99-106.
    PMID: 23856162 DOI: 10.1016/j.ijpharm.2013.06.082
    In our previous study, a novel alginate-based bilayer film for slow-release wound dressings was successfully developed. We found that alginate alone yielded poor films; however, the addition of gelatine had significantly enhanced the drug dispersion as well as the physical properties. Here, an investigation of the drug-polymer interactions in the bilayer films was carried out. Drug content uniformity test and microscopy observation revealed that the addition of gelatine generated bilayer films with a homogenous drug distribution within the matrix. The FTIR and XRD data showed an increase in film crystallinity which might infer the presence of drug-polymer crystalline microaggregates in the films. DSC confirmed the drug-polymer interaction and indicated that the gelatine has no effect on the thermal behaviour of the microaggregates, suggesting the compatibility of the drug and excipients in the bilayer films. In conclusion, the addition of gelatine can promote homogenous dispersion of hydrophobic drugs in alginate films possibly through the formation of crystalline microaggregates.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  6. Ionic liquids toxicity on fresh water microalgae, Scenedesmus quadricauda, Chlorella vulgaris &Botryococcus braunii; selection criterion for use in a two-phase partitioning bioreactor (TPPBR)
    Quraishi KS, Bustam MA, Krishnan S, Aminuddin NF, Azeezah N, Ghani NA, et al.
    Chemosphere, 2017 Oct;184:642-651.
    PMID: 28624742 DOI: 10.1016/j.chemosphere.2017.06.037
    A promising method of Carbon dioxide (CO2) valorization is to use green microalgae photosynthesis to process biofuel. Two Phase Partitioning Bioreactors (TPPBR) offer the possibility to use non-aqueous phase liquids (NAPL) to enhance CO2 solubility; thus making CO2 available to maximize algae growth. This requires relatively less toxic hydrophobic Ionic Liquids (ILs) that comprise a new class of ionic compounds with remarkable physicochemical properties and thus qualifies them as NAPL candidates. This paper concerns the synthesis of ILs with octyl and butyl chains as well as different cations containing aromatic (imidazolium, pyridinium) and non-aromatic (piperidinum, pyrrolidinium) rings for CO2 absorption studies. The authors measured their respective toxicity levels on microalgae species, specifically, Scenedesmus quadricauda, Chlorella vulgaris and Botryococcus braunii. Results revealed that octyl-based ILs were more toxic than butyl-based analogues. Such was the case for bmim-PF6 at double saturation with an absorbance of 0.11, compared to Omim-PF6 at 0.17, bmim-NTf2 at 0.02, and Omim-NTf2 at 0.14, respectively. CO2 uptake results for ILs bearing octyl-based chains compared to the butyl analog were 54% (nCO2/nIL) (i.e., moles of CO2 moles of IL) and 38% (nCO2/nIL), respectively. Conclusively, 1-butyl-1-methylpiperidinium absorbed 13% (nCO2/nIL) and appeared the least toxic, having an absorbance of 0.25 at 688 nm (double saturation at 7 d) compared to 1-butyl-3-methylimidazolium, which showed the highest toxicity with zero absorbance. Accordingly, these findings suggest that 1-butyl-1-methylpiperidinium is capable of transporting CO2 to a system containing green microalgae without causing significant harm; thus allowing its use in TPPBR technology.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  7. Fulltext Preparation, characterisation and biological evaluation of biopolymer-coated multi-walled carbon nanotubes for sustained-delivery of silibinin
    Tan JM, Bullo S, Fakurazi S, Hussein MZ
    Sci Rep, 2020 10 09;10(1):16941.
    PMID: 33037287 DOI: 10.1038/s41598-020-73963-8
    This research work represents the first major step towards constructing an effective therapeutic silibinin (SB) in cancer treatment using oxidised multi-walled carbon nanotubes (MWCNT-COOH) functionalised with biocompatible polymers as the potential drug carrier. In an attempt to increase the solubility and dispersibility of SB-loaded nanotubes (MWSB), four water-soluble polymers were adopted in the preparation process, namely polysorbate 20 (T20), polysorbate 80 (T80), polyethylene glycol (PEG) and chitosan (CHI). From the geometry point of view, the hydrophobic regions of the nanotubes were loaded with water-insoluble SB while the hydrophilic polymers functionalised on the outer surfaces of the nanotubes serve as a protective shell to the external environment. The chemical interaction between MWSB nanocomposites and polymer molecules was confirmed by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. Besides, high-resolution transmission electron microscopy (HR-TEM), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA) and UV-visible spectrophotometry were also employed to characterise the synthesised nanocomposites. The morphological study indicated that the polymers were deposited on the external surfaces of MWSB and the nanocomposites were seen to preserve their tubular structures even after the coating process was applied. The TGA results revealed that the incorporation of biopolymers practically improved the overall thermal stability of the coated MWSB nanocomposites. Evaluation of the in vitro effect on drug release rate by the nanocomposites was found to follow a biphasic release manner, showing a fast release at an initial stage and then a sustained-release over 2500 min. Besides, the drug release mechanisms of the nanocomposites demonstrated that the amount of SB released in the simulated environment was governed by pseudo-second order in which, the rate-limiting step mainly depends on diffusion of drug through chemisorption reaction. Finally, MTT assay showed that the coated MWSB nanocomposites on 3T3 cells were very much biocompatible at a concentration up to 100 g/mL, which is an evidence of MWSB reduced cytotoxicity.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  8. Fulltext Bacterial Cellulose: Production, Characterization, and Application as Antimicrobial Agent
    Lahiri D, Nag M, Dutta B, Dey A, Sarkar T, Pati S, et al.
    Int J Mol Sci, 2021 Nov 30;22(23).
    PMID: 34884787 DOI: 10.3390/ijms222312984
    Bacterial cellulose (BC) is recognized as a multifaceted, versatile biomaterial with abundant applications. Groups of microorganisms such as bacteria are accountable for BC synthesis through static or agitated fermentation processes in the presence of competent media. In comparison to static cultivation, agitated cultivation provides the maximum yield of the BC. A pure cellulose BC can positively interact with hydrophilic or hydrophobic biopolymers while being used in the biomedical domain. From the last two decades, the reinforcement of biopolymer-based biocomposites and its applicability with BC have increased in the research field. The harmony of hydrophobic biopolymers can be reduced due to the high moisture content of BC in comparison to hydrophilic biopolymers. Mechanical properties are the important parameters not only in producing green composite but also in dealing with tissue engineering, medical implants, and biofilm. The wide requisition of BC in medical as well as industrial fields has warranted the scaling up of the production of BC with added economy. This review provides a detailed overview of the production and properties of BC and several parameters affecting the production of BC and its biocomposites, elucidating their antimicrobial and antibiofilm efficacy with an insight to highlight their therapeutic potential.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  9. Fulltext In Silico and In Vitro Study of the Bromelain-Phytochemical Complex Inhibition of Phospholipase A2 (Pla2)
    Mohamed Tap F, Abd Majid FA, Ismail HF, Wong TS, Shameli K, Miyake M, et al.
    Molecules, 2018 Jan 19;23(1).
    PMID: 29351216 DOI: 10.3390/molecules23010073
    Phospholipase A2 (Pla2) is an enzyme that induces inflammation, making Pla2 activity an effective approach to reduce inflammation. Therefore, investigating natural compounds for this Pla2 inhibitory activity has important therapeutic potential. The objective of this study was to investigate the potential in bromelain-phytochemical complex inhibitors via a combination of in silico and in vitro methods. Bromelain-amenthoflavone displays antagonistic effects on Pla2. Bromelian-asiaticoside and bromelain-diosgenin displayed synergistic effects at high concentrations of the combined compounds, with inhibition percentages of more than 70% and 90%, respectively, and antagonistic effects at low concentrations. The synergistic effect of the bromelain-asiaticoside and bromelain-diosgenin combinations represents a new application in treating inflammation. These findings not only provide significant quantitative data, but also provide an insight on valuable implications for the combined use of bromelain with asiaticoside and diosgenin in treating inflammation, and may help researchers develop more natural bioactive compounds in daily foods as anti-inflammatory agent.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  10. Fulltext Identification, structure-activity relationship and in silico molecular docking analyses of five novel angiotensin I-converting enzyme (ACE)-inhibitory peptides from stone fish (Actinopyga lecanora) hydrolysates
    Auwal SM, Zainal Abidin N, Zarei M, Tan CP, Saari N
    PLoS One, 2019;14(5):e0197644.
    PMID: 31145747 DOI: 10.1371/journal.pone.0197644
    Stone fish is an under-utilized sea cucumber with many health benefits. Hydrolysates with strong ACE-inhibitory effects were generated from stone fish protein under the optimum conditions of hydrolysis using bromelain and fractionated based on hydrophobicity and isoelectric properties of the constituent peptides. Five novel peptide sequences with molecular weight (mw) < 1000 daltons (Da) were identified using LC-MS/MS. The peptides including Ala-Leu-Gly-Pro-Gln-Phe-Tyr (794.44 Da), Lys-Val-Pro-Pro-Lys-Ala (638.88 Da), Leu-Ala-Pro-Pro-Thr-Met (628.85 Da), Glu-Val-Leu-Ile-Gln (600.77 Da) and Glu-His-Pro-Val-Leu (593.74 Da) were evaluated for ACE-inhibitory activity and showed IC50 values of 0.012 mM, 0.980 mM, 1.310 mM, 1.440 mM and 1.680 mM, respectively. The ACE-inhibitory effects of the peptides were further verified using molecular docking study. The docking results demonstrated that the peptides exhibit their effect mainly via hydrogen and electrostatic bond interactions with ACE. These findings provide evidence about stone fish as a valuable source of raw materials for the manufacture of antihypertensive peptides that can be incorporated to enhance therapeutic relevance and commercial significance of formulated functional foods.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  11. Impact of biological filtrations for organic micropollutants and polyfluoroalkyl substances removal from secondary effluent
    Pramanik BK, Pramanik SK, Suja F
    Environ Technol, 2016 Aug;37(15):1857-64.
    PMID: 26695189 DOI: 10.1080/09593330.2015.1134677
    The impact of biological activated carbon (BAC), sand filtration (SF) and biological aerated filter (BAF) for removal of the selected organic micropollutants and polyfluoroalkyl substances (PFASs) from secondary effluent was studied. BAC led to greater removal of dissolved organic carbon (43%) than BAF (30%) which in turn was greater than SF (24%). All biological filtration systems could effectively remove most of the selected organic micropollutants, and there was a greater removal of these micropollutants by BAC (76-98%) than BAF (70-92%) or SF (68-90%). It was found that all treatment was effective for removal of the hydrophobic (log D > 3.2) and readily biodegradable organic micropollutants. The major mechanism for the removal of these molecules was biodegradation by the micro-organism and sorption by the biofilm. Compared to organic micropollutants removal, there was a lower removal of PFASs by all treatments, and BAF and SF had a considerably lower removal than BAC treatment. The better removal for all molecule types by BAC was due to additional adsorption capacity by the activated carbon. This study demonstrated that the BAC process was most effective in removing organic micropollutants present in the secondary effluent.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  12. Fulltext Spectrofluorometric and molecular docking studies on the binding of curcumenol and curcumenone to human serum albumin
    Hamdi OA, Feroz SR, Shilpi JA, Anouar el H, Mukarram AK, Mohamad SB, et al.
    Int J Mol Sci, 2015;16(3):5180-93.
    PMID: 25756376 DOI: 10.3390/ijms16035180
    Curcumenol and curcumenone are two major constituents of the plants of medicinally important genus of Curcuma, and often govern the pharmacological effect of these plant extracts. These two compounds, isolated from C. zedoaria rhizomes were studied for their binding to human serum albumin (HSA) using the fluorescence quench titration method. Molecular docking was also performed to get a more detailed insight into their interaction with HSA at the binding site. Additions of these sesquiterpenes to HSA produced significant fluorescence quenching and blue shifts in the emission spectra of HSA. Analysis of the fluorescence data pointed toward moderate binding affinity between the ligands and HSA, with curcumenone showing a relatively higher binding constant (2.46 × 105 M-1) in comparison to curcumenol (1.97 × 104 M-1). Cluster analyses revealed that site I is the preferred binding site for both molecules with a minimum binding energy of -6.77 kcal·mol-1. However, binding of these two molecules to site II cannot be ruled out as the binding energies were found to be -5.72 and -5.74 kcal·mol-1 for curcumenol and curcumenone, respectively. The interactions of both ligands with HSA involved hydrophobic interactions as well as hydrogen bonding.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  13. Production and modification of nanofibrillated cellulose using various mechanical processes: a review
    Abdul Khalil HP, Davoudpour Y, Islam MN, Mustapha A, Sudesh K, Dungani R, et al.
    Carbohydr Polym, 2014 Jan;99:649-65.
    PMID: 24274556 DOI: 10.1016/j.carbpol.2013.08.069
    Nanofibrillated cellulose from biomass has recently gained attention owing to their biodegradable nature, low density, high mechanical properties, economic value and renewability. Although they still suffer from two major drawbacks. The first challenge is the exploration of raw materials and its application in nanocomposites production. Second one is high energy consumption regarding the mechanical fibrillation. However, pretreatments before mechanical isolation can overcome this problem. Hydrophilic nature of nano-size cellulose fibers restricts good dispersion of these materials in hydrophobic polymers and therefore, leads to lower mechanical properties. Surface modification before or after mechanical defibrillation could be a solution for this problem. Additionally, drying affects the size of nanofibers and its properties which needs to study further. This review focuses on recent developments in pretreatments, nanofibrillated cellulose production and its application in nanopaper applications, coating additives, security papers, food packaging, and surface modifications and also for first time its drying.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  14. Preparation and characterization of polyhydroxyalkanoates macroporous scaffold through enzyme-mediated modifications
    Ansari NF, Amirul AA
    Appl Biochem Biotechnol, 2013 Jun;170(3):690-709.
    PMID: 23604967 DOI: 10.1007/s12010-013-0216-0
    Polyhydroxyalkanoates (PHAs) are hydrophobic biodegradable thermoplastics that have received considerable attention in biomedical applications due to their biocompatibility, mechanical properties, and biodegradability. In this study, the degradation rate was regulated by optimizing the interaction of parameters that influence the enzymatic degradation of P(3HB) film using response surface methodology (RSM). The RSM model was experimentally validated yielding a maximum 21 % weight loss, which represents onefold increment in percentage weight loss in comparison with the conventional method. By using the optimized condition, the enzymatic degradation by an extracellular PHA depolymerase from Acidovorax sp. DP5 was studied at 37 °C and pH 9.0 on different types of PHA films with various monomer compositions. Surface modification of scaffold was employed using enzymatic technique to create highly porous scaffold with a large surface to volume ratio, which makes them attractive as potential tissue scaffold in biomedical field. Scanning electron microscopy revealed that the surface of salt-leached films was more porous compared with the solvent-cast films, and hence, increased the degradation rate of salt-leached films. Apparently, enzymatic degradation behaviors of PHA films were determined by several factors such as monomer composition, crystallinity, molecular weight, porosity, and roughness of the surface. The hydrophilicity and water uptake of degraded salt-leached film of P(3HB-co-70%4HB) were enhanced by incorporating chitosan or alginate. Salt-leached technique followed by partial enzymatic degradation would enhance the cell attachment and suitable for biomedical as a scaffold.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  15. Hydrogen bonds in galactopyranoside and glucopyranoside: a density functional theory study
    Mosapour Kotena Z, Behjatmanesh-Ardakani R, Hashim R, Manickam Achari V
    J Mol Model, 2013 Feb;19(2):589-99.
    PMID: 22972691 DOI: 10.1007/s00894-012-1576-z
    Density functional theory calculations on two glycosides, namely, n-octyl-β-D-glucopyranoside (C(8)O-β-Glc) and n-octyl-β-D-galactopyranoside (C(8)O-β-Gal) were performed for geometry optimization at the B3LYP/6-31G level. Both molecules are stereoisomers (epimers) differing only in the orientation of the hydroxyl group at the C4 position. Thus it is interesting to investigate electronically the effect of the direction (axial/equatorial) of the hydroxyl group at the C4 position. The structure parameters of X-H∙∙∙Y intramolecular hydrogen bonds were analyzed, while the nature of these bonds and the intramolecular interactions were considered using the atoms in molecules (AIM) approach. Natural bond orbital analysis (NBO) was used to determine bond orders, charge and lone pair electrons on each atom and effective non-bonding interactions. We have also reported electronic energy and dipole moment in gas and solution phases. Further, the electronic properties such as the highest occupied molecular orbital, lowest unoccupied molecular orbital, ionization energy, electron affinity, electronic chemical potential, chemical hardness, softness and electrophilicity index, are also presented here for both C(8)O-β-Glc and C(8)O-β-Gal. These results show that, while C(8)O-β-Glc possess- only one hydrogen bond, C(8)O-β-Gal has two intramolecular hydrogen bonds, which further confirms the anomalous stability of the latter in self-assembly phenomena.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  16. Multispectroscopic and molecular modeling approach to investigate the interaction of flavokawain B with human serum albumin
    Feroz SR, Mohamad SB, Bujang N, Malek SN, Tayyab S
    J Agric Food Chem, 2012 Jun 13;60(23):5899-908.
    PMID: 22624666 DOI: 10.1021/jf301139h
    Interaction of flavokawain B (FB), a multitherapeutic flavonoid from Alpinia mutica with the major transport protein, human serum albumin (HSA), was investigated using different spectroscopic probes, i.e., intrinsic, synchronous, and three-dimensional (3-D) fluorescence, circular dichroism (CD), and molecular modeling studies. Values of binding parameters for FB-HSA interaction in terms of binding constant and stoichiometry of binding were determined from the fluorescence quench titration and were found to be 6.88 × 10(4) M(-1) and 1.0 mol of FB bound per mole of protein, respectively, at 25 °C. Thermodynamic analysis of the binding data obtained at different temperatures showed that the binding process was primarily mediated by hydrophobic interactions and hydrogen bonding, as the values of the enthalpy change (ΔH) and the entropy change (ΔS) were found to be -6.87 kJ mol(-1) and 69.50 J mol(-1) K(-1), respectively. FB binding to HSA led to both secondary and tertiary structural alterations in the protein as revealed by intrinsic, synchronous, and 3-D fluorescence results. Increased thermal stability of HSA in the presence of FB was also evident from the far-UV CD spectral results. The distance between the bound ligand and Trp-214 of HSA was determined as 3.03 nm based on the Förster resonance energy transfer mechanism. Displacement experiments using bilirubin and warfarin coupled with molecular modeling studies assigned the binding site of FB on HSA at domain IIA, i.e., Sudlow's site I.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  17. Direct recovery of recombinant nucleocapsid protein of Nipah virus from unclarified Escherichia coli homogenate using hydrophobic interaction expanded bed adsorption chromatography
    Chong FC, Tan WS, Biak DR, Ling TC, Tey BT
    J Chromatogr A, 2010 Feb 19;1217(8):1293-7.
    PMID: 20044094 DOI: 10.1016/j.chroma.2009.12.039
    A direct recovery of recombinant nucleocapsid protein of Nipah virus (NCp-NiV) from crude Escherichia coli (E. coli) homogenate was developed successfully using a hydrophobic interaction expanded bed adsorption chromatography (HI-EBAC). The nucleic acids co-released with the recombinant protein have increased the viscosity of the E. coli homogenate, thus affected the axial mixing in the EBAC column. Hence, DNase was added to reduce the viscosity of feedstock prior to its loading into the EBAC column packed with the hydrophobic interaction chromatography (HIC) adsorbent. The addition of glycerol to the washing buffer has reduced the volume of washing buffer applied, and thus reduced the loss of the NCp-NiV during the washing stage. The influences of flow velocity, degree of bed expansion and viscosity of mobile phase on the adsorption efficiency of HI-EBAC were studied. The dynamic binding capacity at 10% breakthrough of 3.2mg/g adsorbent was achieved at a linear flow velocity of 178 cm/h, bed expansion of two and feedstock viscosity of 3.4 mPas. The adsorbed NCp-NiV was eluted with the buffer containing a step gradient of salt concentration. The purification of hydrophobic NCp-NiV using the HI-EBAC column has recovered 80% of NCp-NiV from unclarified E. coli homogenate with a purification factor of 12.5.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  18. Shear flow behaviour and emulsion-stabilizing effect of natural polysaccharide-protein gum in aqueous system and oil/water (O/W) emulsion
    Amid BT, Mirhosseini H
    Colloids Surf B Biointerfaces, 2013 Mar 1;103:430-40.
    PMID: 23261563 DOI: 10.1016/j.colsurfb.2012.11.015
    The main objective of the current work was to characterize the shear rheological flow behaviour and emulsifying properties of the natural biopolymer from durian seed. The present study revealed that the extraction condition significantly affected the physical and functional characteristics of the natural biopolymer from durian seed. The dynamic oscillatory test indicated that the biopolymer from durian seed showed more gel (or solid) like behaviour than the viscous (or liquid) like behaviour (G'>G″) at a relatively high concentration (20%) in the fixed frequency (0.1 Hz). This might be explained by the fact that the gum coils disentangle at low frequencies during the long period of oscillation, thus resulting in more gel like behaviour than the viscous like behaviour. The average droplet size of oil in water (O/W) emulsions stabilized by durian seed gum significantly varied from 0.42 to 7.48 μm. The results indicated that O/W emulsions showed significant different stability after 4 months storage. This might be interpreted by the considerable effect of the extraction condition on the chemical and molecular structure of the biopolymer, thus affecting its emulsifying capacity. The biopolymer extracted by using low water to seed (W/S) ratio at the low temperature under the alkaline condition showed a relatively high emulsifying activity in O/W emulsion.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  19. Fulltext Effects of selected polysorbate and sucrose ester emulsifiers on the physicochemical properties of astaxanthin nanodispersions
    Anarjan N, Tan CP
    Molecules, 2013 Jan 09;18(1):768-77.
    PMID: 23303336 DOI: 10.3390/molecules18010768
    The effects of selected nonionic emulsifiers on the physicochemical characteristics of astaxanthin nanodispersions produced by an emulsification/evaporation technique were studied. The emulsifiers used were polysorbates (Polysorbate 20, Polysorbate 40, Polysorbate 60 and Polysorbate 80) and sucrose esters of fatty acids (sucrose laurate, palmitate, stearate and oleate). The mean particle diameters of the nanodispersions ranged from 70 nm to 150 nm, depending on the emulsifier used. In the prepared nanodispersions, the astaxanthin particle diameter decreased with increasing emulsifier hydrophilicity and decreasing carbon number of the fatty acid in the emulsifier structure. Astaxanthin nanodispersions with the smallest particle diameters were produced with Polysorbate 20 and sucrose laurate among the polysorbates and the sucrose esters, respectively. We also found that the Polysorbate 80- and sucrose oleate-stabilized nanodispersions had the highest astaxanthin losses (i.e., the lowest astaxanthin contents in the final products) among the nanodispersions. This work demonstrated the importance of emulsifier type in determining the physicochemical characteristics of astaxanthin nano-dispersions.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
  20. Solvent accessibility in native and isolated domain environments: general features and implications to interface predictability
    Raih MF, Ahmad S, Zheng R, Mohamed R
    Biophys Chem, 2005 Apr 1;114(1):63-9.
    PMID: 15792862
    A non-redundant database of 4536 structural domains, comprising more than 790,000 residues, has been used for the calculation of their solvent accessibility in the native protein environment and then in the isolated domain environment. Nearly 140,000 (18%) residues showed a change in accessible surface area in the above two conditions. General features of this change under these two circumstances have been pointed out. Propensities of these interfacing amino acid residues have been calculated and their variation for different secondary structure types has been analyzed. Actual amount of surface area lost by different secondary structures is higher in the case of helix and strands compared to coil and other conformations. Overall change in surface area in hydrophobic and uncharged residues is higher than that in charged residues. An attempt has been made to know the predictability of interface residues from sequence environments. This analysis and prediction results have significant implications towards determining interacting residues in proteins and for the prediction of protein-protein, protein-ligand, protein-DNA and similar interactions.
    Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links