Stability against aggregation of bovine casein micelles in the presence of acidic and alkaline gelatin

The effect of the presence of colloidal dispersed and molecular dispersed acidic (type A) and alkaline (type B) gelatins with similar molecular weight and size but different isoelectric points (7.9 and 4.9) on the stability against aggregation of bovine casein micelles was investigated by turbidimetric titration and laser techniques, over a wide range of biopolymers concentrations, gelatin/casein ratio in the initial mixture (0.03–20), pH (4.9–6.7) and ionic strength (10⁻³(milk salts)–1.0 NaCl), using glucono-δ-lactone (GL) as acidifier. Aggregates of acid gelatin A interact with the oppositely charged micellar casein at an ionic strength of around 10⁻³(milk salts) and pH 6.7 resulting in the formation of an electroneutral complex by ionic bonds between the carboxyl groups of casein and the amino groups of the gelatin molecules. The complexes obtained are polynuclear, the aggregation of which is not as sensitive to pH as that of free casein micelles. Aggregation of such complexes is the result of bridging flocculation. The “molar” ratio gelatin aggregates/casein micelles in the mixed aggregates is 4/1. The complexes are formed and stabilised via electrostatic interaction rather than through hydrogen bonds or hydrophobic interaction. In the presence of an excess of gelatin molecules in the initial mixture a charged gelatin–casein complex forms and some dissociation of casein micelles occurs and, as a consequence, soluble complexes are obtained. During the addition of alkaline gelatin B aggregates to the micellar casein solution and subsequent acidification of the mixture by GL, no effect of the presence of gelatin B on the stability of micellar casein was observed. Received: 28 March 2000 Accepted: 5 October 2000     

Micellar behavior of acrylamide– octylphenylpoly(oxyethylene) acrylate copolymer in aqueous solution

The copolymer of acrylamide and octylphenylpoly(oxyethylene) acrylate macromonomer (AM-C₈PhEO₇Ac) was synthesized and characterized by IR and NMR spectroscopy. The molecular weight of the copolymer was determined to be 1.21 × 10⁵ by static light scattering. The weight contents of AM and macromonomer were determined to be 67.8 and 32.2%, respectively, by elemental analysis. The micellar behavior of the copolymer in aqueous solution was studied by UV spectroscopy and atomic force microscopy (AFM). The molecules of AM-C₈PhEO₇Ac copolymer form monomolecular micelles in the concentration range 4 × 10⁻⁶ – 3 × 10⁻⁵ g/ml and polymolecular micelles at concentrations above 3 × 10⁻⁵ g/ml according to the UV analysis. The AFM images indicate that the monomolecular micelles are globular with diameters of 70 nm and have a narrow size distribution. The polymolecular micelles can be globular or cylindrical depending on the concentration, and have a wide size distribution. Received: 10 February 1999 Accepted in revised form: 28 June 1999     

Low-concentration aqueous solutions of undecenoic acid and sodium undecenoate

The behaviors of low-concentration aqueous solutions of 10-undecenoic acid and its sodium salt were studied by several techniques. The acid does not have a critical micelle concentration, but gives an emulsion of very small droplets at (0.8–1) ×  10⁻⁴ mol dm⁻³. The emulsion was clearly visible by eye at 0.002 mol dm⁻³. The sodium salt has a stepwise aggregation process, giving premicellar aggregates at 0.023 ± 0.008 mol dm⁻³, which grow to form micelles at 0.117 ± 0.007 mol dm⁻³. The compositions of the solution and the micelles were also studied. Received: 25 February 1999 Accepted in revised form: 21 June 1999     

Impedance studies on the 5-V cathode material,LiCoPO<Subscript>4</Subscript>

Olivine-structured LiCoPO₄ is synthesized by a Pechini-type polymer precursor method. The structure and the morphology of the compounds are studied by the Rietveld-refined X-ray diffraction, scanning electron microscopy, Brunauer, Emmett, and Teller surface area technique, infrared spectroscopy, and Raman spectroscopy techniques, respectively. The ionic conductivity (σ ionic), dielectric, and electric modulus properties of LiCoPO₄ are investigated on sintered pellets by impedance spectroscopy in the temperature range, 27–50 °C. The σ (ionic) values at 27 and 50 °C are 8.8 × 10⁻⁸ and 49 × 10⁻⁸ S cm⁻¹, respectively with an energy of activation (E _a) = 0.43 eV. The electric modulus studies suggest the presence of non-Debye type of relaxation. Preliminary charge–discharge cycling data are presented.     

Laser Raman spectroscopic study of water in gelatin–surfactant solutions and gels

A Raman spectroscopic study was carried out on water in gelatin at 4% w/v in gel (25 °C) and sol (40–60 °C) states at various concentrations (0.5, 1, 5, 10 and 15 mM) of anionic surfactant, sodium dodecyl sulfate (SDS). The in-phase collective stretching mode vibration of hydrogen-bonded -OH oscillators, centered around 3250 cm⁻¹ in a tetrahedral network of water molecules, was observed to be significantly affected by temperature and the presence of SDS. According to our observation this may be due to the thinning of the hydration water around the gelatin molecules due to strong thermal agitation. The peak center of the collective bands of water decreased linearly with SDS concentration in the gel state which implied that with the increase in concentration of SDS, the -OH oscillators gradually lost their attachment to gelatin chains and were replaced by SDS molecules. Ultimately this resulted in a thinning of the hydration layer around the gelatin and the oscillation frequency of -OH oscillators moved towards 3250 cm⁻¹ at 1 mM SDS concentration resulting in increased coupling of -OH oscillators to form the tetrahedral network at the critical micelle concentration (cmc) of SDS. The variation in the peak amplitudes and the systematic reversal of their trend about the cmc axis was surprising. At 40 °C the amplitude of the peak at 3250 cm⁻¹ increased drastically due to a possible coil expansion by about 7–8% which accommodated more interstitial water into the pseudonetwork leading to an increase in the number of nearest neighbors and for about 6% increase in the C value. However, at the cmc the peak amplitude was observed to be independent of temperature. Continuous shifting of the peak center and full width at half-maxima towards lower values was observed with increasing SDS concentrations in the gel state. Received: 28 September 1998 Accepted in revised form: 8 March 1999     

Enhanced electrochemical properties of polyethylene oxide-based composite solid polymer electrolytes with porous inorganic–organic hybrid polyphosphazene nanotubes as fillers

Solid composite polymer electrolytes consisting of polyethylene oxide (PEO), LiClO₄, and porous inorganic–organic hybrid poly (cyclotriphosphazene-co-4, 4′-sulfonyldiphenol) (PZS) nanotubes were prepared using the solvent casting method. Differential scanning calorimetry and scanning electron microscopy were used to determine the characteristics of the composite polymer electrolytes. The ionic conductivity, lithium ion transference number, and electrochemical stability window can be enhanced after the addition of PZS nanotubes. The electrochemical impedance showed that the conductivity was improved significantly. Maximum ionic conductivity values of 1.5 × 10⁻⁵ S cm⁻¹ at ambient temperature and 7.8 × 10⁻⁴ S cm⁻¹ at 80 °C were obtained with 10 wt.% content of PZS nanotubes, and the lithium ion transference number was 0.35. The good electrochemical properties of the solid-state composite polymer electrolytes suggested that the porous inorganic–organic hybrid polyphosphazene nanotubes had a promising use as fillers in SPEs and the PEO₁₀–LiClO₄–PZS nanotube solid composite polymer electrolyte might be used as a candidate material for lithium polymer batteries.     

Analysis of amino acid neurotransmitters by capillary electrophoresis and laser-induced fluorescence using a new fluorescein-derived label

A capillary electrophoresis laser-induced fluorescence detection method (CE-LIF) was developed for the separation of eight neurotransmitters tagged on their amino function with 6-oxy-(N-succinimidyl acetate)-9-(2′-methoxycarbonyl) fluorescein (SAMF), a new fluorescent reagent synthesized in our lab. Derivatization was performed in boric acid buffer (pH = 7.75) at 37 °C over 15 min. The pH-independent fluorescence of SAMF (pH 4–9) permits background buffers over a wide range of pH. It was demonstrated that an acidic running buffer offers a better resolution compared to basic medium in terms of resolution and peak shapes. Employing Cu²⁺ as the additive, the molecules were baseline-separated using a running buffer consisting of 40 mM sodium acetate and 2 mM Cu²⁺ (pH 6.0). The detection limits ranged from 1 to 2 × 10⁻¹⁰ M. The method has been validated for the characterization of lymphocyte samples. The results obtained illustrate the advantages of combining SAMF derivatization with CE-LIF for determining neurotransmitters.     

Kinetic Determination of Nanogram Levels of Manganese(II) by Naphthol Blue Black–Potassium Periodate–1,10-Phenanthroline System

 The catalytic effect of manganese(II) on the oxidation of Naphthol Blue Black, with potassium periodate in the presence of 1,10-phenanthroline in weakly acidic media is studied. The reaction is followed spectrophotometrically by measuring the decrease in the absorbance of the dye at 618 nm. Under the optimum conditions (3 × 10⁻⁵ mol dm⁻³ Naphthol Blue Black, 6 × 10⁻⁴ mol dm⁻³ potassium periodate, 1 × 10⁻⁴ mol dm⁻³ 1,10-phenanthroline, 0.1 mol dm⁻³ acetate buffer – pH 4.0, 60 °C, 5 min) manganese(II) in the range 0.08–4 ng cm⁻³ can be determined by the fixed-time method with a detection limit of 0.025 ng cm⁻³. The influence of foreign ions on the accuracy of the results is investigated. The developed method is highly sensitive, selective, and simple. The method was applied successfully to the determination of manganese in cucumbers, garlic cloves and parsley leaves. Received June 12, 2000. Revision December 12, 2000.     

Effect of Amines on the Surface Charge Properties of Iron Oxides

Specific studies detailing the effects of amines, used as pH control agents for corrosion inhibition in power plants, on the surface charge of iron oxides provide data to assess the mechanism of how these amines impact deposition rate. The current study was undertaken in order to determine accurately the dissociation constants of the relevant amines at Pressurized Water Reactor (PWR) operating conditions and to investigate the effect of sorption of two of these amines (morpholine and dimethylamine) by magnetite. The acid-dissociation equilibria of morpholine (MOR), dimethylamine (DMA) and ethanolamine (ETA) were measured potentiometrically with a hydrogen-electrode concentration cell (HECC) from 0 to 290 °C in sodium trifluoromethanesulfonate (NaTr) solutions at ionic strengths up to 1 mol⋅kg⁻¹. Magnetite surface titrations were performed at an ionic strength of 0.03 mol⋅kg⁻¹ (NaTr medium) in the presence or absence of morpholine and dimethylamine buffers over a wide range of pH and total amine concentrations at 150–250 °C. D.A. Palmer is retired.     

Polydisperse fractal aggregate formation in clay mineral and iron oxide suspensions, pH and ionic strength dependence

pH- and ionic-strength-dependent aggregation of permanently and conditionally charged clay mineral (montmorillonite) and iron oxide (magnetite) particles was investigated by means of dynamic light scattering and rheology. An indifferent electrolyte (NaCl) was used. The surface charging of solids was determined by acid–base titration. The point of zero charge (PZC) of magnetite seemed to be at pH 8.0 ± 0.1. The permanent negative charges on the basal plane of montmorillonite influence the interfacial distribution of H⁺ and Na⁺ ions. The pH dependence of the electrophoretic mobility showed directly the dominance of negative charges on montmorillonite lamellae independently of pH, while for magnetite the sign of the mobility reversed at pH ˜ 8.0. Montmorillonite particles formed stable suspensions; coagulation did not take place below 35 mM 1:1 electrolyte independently of pH. The aggregation of magnetite sol becomes significant near the pH of the PZC even at low ionic strength. Colloidal stability in composite systems was investigated at pH ˜ 4, where oxide and clay mineral particles are oppositely charged. At the lowest NaCl concentrations (1, 5 mM) the mixed systems remained stable and aggregation of oppositely charged particles could not be observed at all. Heterocoagulation of dissimilar particles needed a definite amount of dissolved electrolytes (about 8 mM). Mixed clay mineral and oxide systems are more sensitive to electrolyte under acidic conditions than those separately. Rheological investigation of the mixed clay mineral–oxide suspensions at pH ˜ 4 provided proof for the absence of attractive particle interaction at low ionic strength (2 mM). A physical network of oppositely charged particles could form only at higher salt concentration, for example, in the presence of 10 mM NaCl. The yield value of plastic systems showed a significant maximum at 1:15 magnetite/montmorillonite mass ratio. Received: 21 November 2000 Accepted: 20 December 2000     

Surface active and aggregation behavior of methylimidazolium-based ionic liquids of type [Cnmim] [X], n?=?4, 6, 8 and [X]?=?Cl?, Br?, and I? in water

The surface active and aggregation behavior of ionic liquids of type [C _n mim][X] (1-alkyl-3-methylimidazolium (mim) halides), where n = 4, 6, 8 and [X] = Cl⁻, Br⁻ and I⁻ was investigated by using three techniques: surface tension, ¹H nuclear magnetic resonance (NMR) spectroscopy, small-angle neutron scattering (SANS). A series of parameters including critical aggregation concentrations (CAC), surface active parameters and thermodynamic parameters of aggregation were calculated. The ¹H NMR chemical shifts and SANS measurements reveal no evidence of aggregates for the short-chain 1-butylmim halides in water and however small oblate ellipsoidal shaped aggregates are formed by ionic liquids with 1-hexyl and 1-octyl chains. Analysis of SANS data analysis at higher concentrations of [C₈mim][Cl] showed that the microstructures consist of cubically packed molecules probably through π–π and hydrogen bond interactions.     

Flavonol Derivatives for Determination of Cr(III) and W(VI)

 Simple, rapid, sensitive and selective methods for the determination of Cr(III) and W(VI) with flavonol derivatives in the presence of surface-active agents are proposed. In the pH ranges 3.4–4.2 and 1.9–2.5, the molar absorptivities of Cr(III)-morin-emulsifier S (EFA) and W(VI)-morin-polyvinylpyrrolidone (PVP) systems are 1.13×10⁵ and 2.13×10⁴ L mol⁻¹ cm⁻¹ at 435 and 415 nm, respectively. The Cr(III)-quercetin-PVP and W(VI)-quercetin-cetylpyridinium bromide (CPB) systems are formed in the pH ranges 4–4.6 and 2.2–2.8 with molar absorptivities 1.02×10⁵ and 9.02×10⁴ L. mol⁻¹ cm⁻¹ at 441 and 419 nm, respectively. The linear dynamic ranges for the determination of Cr(III) and W(VI) with morin in the presence of EFA and PVP are 0.03–0.46 and 0.71–8.1 μg mL⁻¹, respectively. The corresponding ranges with quercetin are 0.04–0.54 and 0.14–2.1 μg mL⁻¹ of Cr(III) and W(VI), respectively. The r.s.d (n = 10) for the determination of 0.25 and 3.7 μg mL⁻¹ of Cr(III) and W(VI) with morin and their detection limits are 0.88 and 0.99% and 0.016 and 0.63 μg mL⁻¹, respectively. Using quercetin, the r.s.d (n = 10) for 0.22 and 1.2 μg mL⁻¹ of Cr(III) and W(VI) and their detection limits are 0.92 and 0.91% and 0.015 and 0.08 μg mL⁻¹, respectively. The critical evaluation of the proposed methods is performed by statistical analysis of the experimental data. The proposed methods are applied to determine Cr in steel, non-ferrous alloys, wastewater and mud filtrate and to the determination of W in steel. Received March 8, 1999. Revision January 21, 2000.     

Thermal and dielectric properties of PEO/EC/Pr4N+I− polymer electrolytes for possible applications in photo-electro chemical solar cells

The anion-conducting polymer electrolyte polyethylene oxide (PEO)/ethylene carbonate (EC)/Pr₄N⁺I⁻/I₂ is a candidate material for fabricating photo-electrochemical (PEC) solar cells. Relatively high ionic conductivity values are obtained for the plasticized electrolytes; at room temperature, the conductivity increases from 7.6 × 10⁻⁹ to 9.5 × 10⁻⁵ S cm⁻¹ when the amount of EC plasticizer increases from 0% to 50% by weight. An abrupt conductivity enhancement occurs at the melting of the polymer; above the melting temperature, the conductivity can reach values of the order of 10⁻³ S cm⁻¹. The melting temperature decreases from 66.1 to 45.1 °C when the EC mass fraction is increased from 0% to 50%, and there is a corresponding reduction in the glass transition temperature from −57.6 to −70.9 °C with the incorporation of the plasticizer. The static dielectric constant values, , increase with the mass fraction of plasticizer, from 3.3 for the unplasticized sample to 17.5 for the 50% EC sample. The dielectric results show only small traces of ion-pair relaxations, indicating that the amount of ion association is low. Thus, the iodide ion is well dissociated, and despite its large size and relatively low concentration in these samples, the iodide ion to ether oxygen ratio is 1:68, a relatively efficient charge carrier. A further enhancement of the ionic conductivity, especially at lower temperatures, is however desired for these applications.     

Miniaturized Verapamil Soild-State Potentiometric Sensors Based on Native Ionic Polymers

 Novel miniaturized carboxylated poly(vinyl chloride) and poly fluoro sulfonate (Nafion) matrix membrane sensors in an all-solid state graphite support were developed, electrochemically evaluated and used for the assay of verapamil drug. These sensors incorporate the native polymers without plasticizer and/or drug-ion pair complex. Upon soaking these sensors in verapamil test solution, electroactive self regenerated membranes are formed and a near-Nernstian potentiometric response is induced for verapamil over the concentration range 1×10⁻²–1×10⁻⁵ M with a cationic slope of 56–57 mV decade⁻¹ of concentration. Inherent advantages of these sensors include fast response (<10 s), long life time (>6 months), good thermal stability (up to 60 °C), high sensitivity (down to 1 μg ml⁻¹), extended working pH range (2–8) and reasonable selectivity. Verapamil could be determined in various dosage forms with an average recovery of 98.8% (st.dev. 0.8%) of the nominal concentration without any significant interferences from various excipients and diluents commonly used in drug formulations. Received August 17, 1998. Revision February 9, 1999.     

Ion specificity and viscosity of rutile dispersions

The isoelectric point (IEP) of rutile is shifted to higher pH values in the presence of greater than 10⁻⁴ mol dm⁻³ Ba²⁺, Ca²⁺ and Mg²⁺, and when a critical concentration (5 × 10⁻⁴ mol dm⁻³ for Ba²⁺ and 1 × 10⁻³ mol dm⁻³ for Ca²⁺) is exceeded there is no IEP at all and the ζ potential is always positive. A common intersection point for the ζ-potential curves of the different concentrations of salt is found, but for the various salts the point is shifted from ζ = 0 mV for Mg²⁺ up to ζ = 20 mV for Ba²⁺. Between the IEP and the charge-reversal point a rheologically unstable region is discovered. The shear stress of rutile dispersions (2.5 g rutile + 4 g electrolyte solution) at shear rates of 116 s⁻¹ shows the same pH dependence irrespective of the concentration of alkaline-earth metal cations up to 10⁻² mol dm⁻³. The shear stress is less than 1 Pa below pH 3.8 and in the pH range 5–12 it assumes a value between 50 and 80 Pa at 116 s⁻¹ with some scatter; however, no systematic trend with concentration of alkaline-earth metal cations and a rather insignificant decrease with pH at pristine conditions are observed. The acidic branch of the yield stress (pH) and low shear rate viscosity (pH) curves is insensitive to the presence of alkaline-earth metal cations, and the same behaviour is found for the ζ potential. The alkaline-earth metal cations induce an increase in viscosity in the basic region and a shift in the pH of maximum viscosity to high pH values. It was also discovered that the effect different alkaline-earth metal cations have on the rheological properties at the same concentration is different from the effect induced by indifferent electrolytes. When the ζ potential increases the viscosity at high pH is increased in a series which follows the increase in size of the cation. Received: 9 September 1998 Accepted in revised form: 12 January 1999     

Covalent Modification of Glassy Carbon Electrode with L-Cysteine for the Determination of Acetaminophen

A novel L-cysteine film modified electrode has been fabricated by means of an electrochemical oxidation procedure, and it was successfully applied to the electrochemical determination of acetaminophen. This method utilizes the electrooxidation of amines to their analogous cation radicals to form a chemically stable covalent linkage between the nitrogen atom of the amine and edge plane sites at the glassy carbon electrode surface. The electrochemical behaviour of acetaminophen at the film electrode was investigated in 0.1 mol L⁻¹ phosphate buffer (pH 6.20). It was found that the redox peak current of acetaminophen was enhanced greatly on the film electrode. Linearity between the oxidation peak current and the acetaminophen concentration was obtained in the range of 1.0 × 10⁻⁴–2.0 × 10⁻⁷ mol L⁻¹ with a detection limit of 5.0 × 10⁻⁸ mol L⁻¹. For seven parallel detections of 1.0 × 10⁻⁵ mol L⁻¹ acetaminophen, the relative standard deviation (RSD) was 1.46%, suggesting that the film electrode has excellent reproducibility. Application to the determination of acetaminophen in drug tablets and human urine demonstrated that the film electrode has good stability and high sensitivity.     

Solid-state Cu (II) ion-selective electrode based on polyaniline-conducting polymer film doped with copper carmoisine dye complex

A pencil graphite electrode coated by copper (II)–carmoisine dye complex in polyaniline (emeraldine base form) matrix (termed as PGE/PA/Cu-Car) was prepared and used as copper ion-selective electrode. The introduced electrode was found to have high selectivity toward copper ion (II) and exhibited wide working concentration range, low response time, and good shelf life. The sensor electrode showed a linear Nernstian response over the range of 5.0 × 10⁻⁶ to 1.0 × 10⁻¹ M with a slope of 29.7 ± 1 mV per decade change in concentration. A detection limit of 2.0 × 10⁻⁶ M was obtained. The optimum pH working range of the electrode was found to be 4.0–7.0.     

Development of a cloud point extraction and preconcentration method for silver prior to flame atomic absorption spectrometry

The possibility was investigated of using 2-mercaptobenzothiazole (MBT) for Ag(I) concentration by micellar extraction at cloud point (CP) temperature and subsequent determination by flame atomic absorption spectrometry (FAAS). The method is based on the complexation of Ag(I) with 2-mercaptobenzothiazole (MBT) in the presence of non-ionic micelles of Triton X-114. The effect of experimental conditions such as pH, concentration of chelating agent and surfactant, equilibration temperature and time on cloud point extraction was studied. Under the optimum conditions, the preconcentration of 10 mL of water sample in the presence of 0.1% Triton X-114 and 2 × 10⁻⁴ mol L⁻¹ 2-mercaptobenzothiazole permitted the detection of 2.2 ng mL⁻¹ silver. The calibration graph was linear in the range of 10–200 ng mL⁻¹, and the recovery of more than 99% was achieved. The proposed method was used in FAAS determination of Ag(I) in water samples.     

Photoexcitation of the potassium octacyanotungstate(IV)· 5–nitro-1,10–phenanthroline system: kinetics and mechanism of the reaction

The kinetics of thermal reactions of the photochemically-generated species [W(CN)7OH]4− and [W(CN)6–(CNH)(H2O)]2− with 5–nitro-1,10–phenanthroline (nitrophen) in basic and acidic media, respectively, were studied in buffer solutions at pH 4.2–10.6 and ionic strength 7.5×10−2kg−1 at 20°C. The quantum yield for the formation of the photoproduct was calculated and found to depend upon pH and the ligand and [W(CN)8]4− concentrations. The rate constants and quantum yields were less compared with 1,10–phenanthroline due to the electron-withdrawing inductive effect of the nitro group in nitrophen, which makes the latter a weaker ligand. The pseudo-first-order rate constant and quantum yield values in acidic media are higher than in basic media and the mechanisms of the photochemical substitution are different in the two media. This revised version was published online in June 2006 with corrections to the Cover Date.     

Banana Peel: A Potential Substrate for Laccase Production by <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis> VkJ2.4.5 in Solid-State Fermentation

In solid-state fermentation, among various solid supports evaluated, banana peel was found to be an ideal support and resulted into higher levels of laccase (6281.4 ± 63.60 U l⁻¹) along with notable levels of manganese peroxidase production (1339.0 ± 131.23 U l⁻¹) by Aspergillus fumigatus VkJ2.4.5. Maximum levels of laccase was achieved under derived conditions consisting of 80% of moisture level, 6 days of incubation period, 6% inoculum level, and an aeration level of 2.5 l min⁻¹. A column-tray bioreactor was designed to scale up and economize the enzyme production in three successive cycles of fermentation using the same fungal biomass. Thermal and pH stability profiles revealed that enzyme was stable up to 50°C and at varying pH range from 5–9 for up to 2 h. The apparent molecular weight of laccase was found to be 34 ± 1 kDa. MALDI-TOF/TOF analysis of the protein showed significant homology with maximum identity of 67% to other laccases reported in database.