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ß-Galactosidase production, partial purification and characterization by a new fungal were investigated. Partial purification was performed by aqueous two-phase system (ATPS) using polyethylene glycol (PEG) molar mass, PEG concentration, citrate concentration and pH as the independent variables. Purification factor (PF), partition coefficient (K) and yield (Y) were the responses. After identification by rDNA sequencing and classification as Cladosporium tenuissimum URM 7803, this isolate achieved a maximum cell concentration and ß-galactosidase activity of 0.48 g/L and 462.1 U/mL, respectively. ß-Galactosidase partitioned preferentially for bottom salt-rich phase likely due to hydrophobicity and volume exclusion effect caused in the top phase by the high PEG concentration and molar mass. The highest value of PF (12.94) was obtained using 24% (w/w) PEG 8000 g/mol and 15% (w/w) citrate, while that of Y (79.76%) using 20% (w/w) PEG 400 g/mol and 25% (w/w) citrate, both at pH 6. The enzyme exhibited optimum temperature in crude and ATPS extracts in the ranges 35-50 °C and 40-55 °C, respectively, and optimum pH in the range 3.0-4.5, with a fall of enzyme activity under alkaline conditions. Some metal ions and detergents inhibited, while others stimulated enzyme activity. Finally, C. tenuissimum URM 7803 ß-galactosidase showed a profile suitable for prebiotics production.

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The main goal of this work was to evaluate the performance of ß-galactosidase from Exiguobacterium acetylicum MF03 in both hydrolysis and transgalactosylation reactions from different substrates. The enzyme gene was expressed in Escherichia coli BL21 (DE3), sequenced, and subjected to bioinformatic and kinetic assessment. Results showed that the enzyme was able to hydrolyze lactulose and o-nitrophenyl-ß-d-galactopyranoside, but unable to hydrolyze lactose, o-nitrophenyl-ß-d-glucopyranoside, butyl- and pentyl-ß-d-galactosides. This unique and novel substrate specificity converts the E. acetylicum MF03 ß-galactosidase into an ideal catalyst for the formulation of an enzymatic kit for lactulose quantification in thermally processed milk. This is because costly steps to eliminate glucose (resulting from hydrolysis of lactose when a customary ß-galactosidase is used) can be avoided.

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Mixed Mode Chromatography (MMC) is a potential separation technique that allows simultaneous ionic and hydrophobic interactions between the adsorbent and the adsorbate. The aim of this work was to assess the recovery and purification of a Kluyveromyces lactis ß-galactosidase employing MMC. Protein precipitation and dialysis were performed in order to concentrate the enzyme of interest and eliminate cell debris and other interferences inherent in the fermentation medium. The best conditions for both adsorption and desorption were attained by a non-factorial Central Composite Experimental Design and employed in the chromatographic runs with resin CAPTO MMC. Fermentation yielded mean values of total enzyme concentration of 0.44 mg/mL, enzymatic activity (employing lactose as a substrate) of 74 U/mL and specific activity of 168 U/mg. The Purification Factor (PF) obtained was of 1.17. After precipitation and dialysis, the subsequent chromatographic run resulted in recovery values ​​of 41.0 and 48.2% of total protein concentration and enzymatic activity, respectively. SDS-PAGE electrophoresis confirmed the purification evolution throughout the unit operations employed, attesting the feasibility of the technique to obtain enzymes with not only considerable degree of purity but also possessing high-added value.

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ß-Galactosidase is a hydrolase enzyme that catalyzes the hydrolysis of ß-galactosides into monosaccharides; its major application in the food industry is to reduce the content of lactose in lactic products. The aim of this work is to recover this enzyme from a cell lysate by adsorption onto Streamline-DEAE in an expanded bed, avoiding, as much as possible, biomass deposition onto the adsorbent matrix. So as to achieve less cell debris-matrix interaction, the adsorbent surface was covered with polyvinyl pyrrolidone. The enzyme showed to bind in the same extent to naked and covered Streamline-DEAE (65 mg ß-gal/g matrix) in batch mode in the absence of any biomass. The kinetics of the adsorption process was studied and no effect of the polyvinyl pyrrolidone covering was found. The optimal conditions for the recovery were achieved by using a lysate made of 40% wet weight of cells, a polyvinyl pyrrolidone-covered matrix/lysate ratio of 10% and carrying out the adsorption process in expanded bed with recirculation over 2h in 20 mM phosphate buffer pH 7.4. The fraction recovered after the elution contained 65% of the initial amount of enzyme with a 12.6-fold increased specific activity with respect to the lysate. The polyvinyl pyrrolidone content in the eluate was determined and found negligible. The remarkable point of this work is that it was possible to partially purify the enzyme using a feedstock containing an unusually high biomass concentration in the presence of polyvinyl pyrrolidone onto weak anion exchangers.

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Este estudo demonstra como a Beta-galactosidase pode ser desativada e reativada usando EDTA e íons metálicos divalentes. A enzima foi desativada após 20 minutos na presença de EDTA. Desativação máxima para a menor concentração de EDTA (10-3 mol.L-1) ocorreu na presença do tampão Tris-HCl. A enzima recuperou 50% de sua atividade inicial após 10 minutos na presença de Mg2+ em concentrações superiores a 0,1mmol.L-1.Concentrações de 10-4 e 10-3 mol.L-1 de Mn2+ e Co2+ foram suficientes para reativar a enzima em 300% comparado ao controle de íons Mn2+ e aproximadamente 100% para íons Co2+. A enzima perdeu gradualmente a sua atividade quando a concentração foi de 10-2 mol.L-1. Ni2+ e Zn2+ foram incapazes de restabelecer a atividade catalítica. Km app e Vmax app foram 1,95 ± 0,05 mmol.L-1 e 5,40 ± 0,86 x 10-2 mmol.min-1.mg-1. A temperatura e pH ótimos foram 34ºC e 7,5. A meia vida da holoenzima foi de 17,5 min a 30ºC e para a apoenzima foi de 11,0 min a 30ºC. Quanto à variação de pH, a apoenzima provou ser mais sensível que a holoenzima.

In this study, it was demonstrated that Beta-galactosidase can be deactivated and reactivated with EDTA and divalent metal ions. The enzyme was deactivated after 20 minutes in EDTA solution. Maximal deactivation at the lowest EDTA concentration (10-3 mol.L-1) occurred in the presence of Tris-HCl buffer (pH 7.0). The enzyme recovered 50% of its initial activity after 10 minutes at Mg2+concentrations higher than 0.1 mmol.L-1. Experimental concentrations of 0.1 mmol.L-1 Mn2+ and 1.0 mmol.L-1 Co2+ were sufficient to reactivate the enzyme to around 300% of the control activity for the Mn2+ ion and nearly 100% for the Co2+ ion. The enzyme gradually lost its activity when the Co2+ concentration was 10-2 mol.L-1. Ni2+ and Zn2+ were unable to restore the catalytic activity. Km app and Vmax app were 1.95 ± 0.05 mmol.L-1 and 5.40 ± 0.86x10-2 mmol.min-1.mg-1, with o-NPG as substrate. Optimal temperature and pH were 34oC and 7.5. The half-life (t1/2) at 30ºC was 17.5 min for the holoenzyme and 11.0 min for the apoenzyme. With respect to pH variation, the apoenzyme proved to be more sensitive than the holoenzyme.

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AmpC â-lactamases are cephalosporinases that hydrolyze cephamycins as well as other extended-spectrum cephalosporins and are poorly inhibited by clavulanic acid. Although reported with increasing frequency, the true rate of occurrence of AmpC â-lactamases in different organisms, including members of Enterobacteriaceae, remains unknown. The present study was designed to determine the occurrence of AmpC enzyme-harbouring Gram-negative clinical isolates in a tertiary care hospital in Pondicherry state, South India. A total of 235 Gram negative clinical isolates were tested for resistance to cefoxitin, third generation cephalosporin (3GC) antibiotics, ampicillin, amikacin, co-trimoxazole, gentamicin, meropenem and tetracycline by disc diffusion method. Isolates found resistant to 3GC and cefoxitin were tested for the production of AmpC â -lactamases by three dimensional extraction method and AmpC disc method. Isolates found to sensitive to 3GC were subjected to disc antagonism test for inducible AmpC production. One hundred and thirty four (57 percent) strains were resistant to 3GC, among which 63(47 percent) were positive for plasmid-mediated AmpC beta lactamases production. Among the 101 strains sensitive to 3GC, 23 (22.7 percent) revealed the presence of inducible AmpC beta lactamases by disc approximation test. A total of 80.9 percent (51/63) of screen positive isolates were detected by Amp C disc test and 93.6 percent (59/63) by three dimensional extraction method. Out of the 86 AmpC producers, 67 (77.9 percent) were cefoxitin resistant .Inducible AmpC was not found in Esch.coli and Klebsiella spp. The AmpC producers also concurrently showed multidrug resistance pattern. AmpC producers were found to be prevalent in our hospital and though three dimensional extraction test detects AmpC better, the disk test is easier to perform routinely and is user- friendly.

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A total of 187 isolates from 470 clinical specimens were collected from three hospitals in El-Minia governorate and identified as 132 Staphylococcus aureus strains and 55 coagulase-negative staphylococci (CoNS) strains. Susceptibility of isolates to antimicrobial agents was tested by the agar dilution method. The isolated S. aureus strains showed low resistance to vancomycin (1.5 percent), amikacin (2.3 percent) and gatifloxacin (3.8 percent). Vancomycin was the most effective antibiotic against CoNS. The ampicillin-resistant isolates were tested for â-lactamase production where, 61.7 percent of S. aureus and 42.9 percent of CoNS were positive for â-lactamase enzyme. Beta-lactamase producing strains were screened for their plasmid profile using alkaline lysis method. Some of these strains carried at least one plasmid suggesting plasmid-mediated antibiotic resistance. When cells of these strains were exposed to curing agent ethidium bromide, the production of the â-lactamase was lost. Resistance by efflux was studied by a modified fluorometric assay. Addition of uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP) increased norfloxacin accumulation in quinolone resistant S. aureus strains, suggesting endogenous energy-dependent efflux. Combinations of ciprofloxacin with four antimicrobial agents against methicillin resistant S.aureus (MRSA) strains were investigated using decimal assay for additivity (DAA) technique. Synergistic interaction was observed between ciprofloxacin and oxacillin. ciprofloxacin plus cefepime and gentamicin appeared to be additive, while ciprofloxacin plus erythromycin was antagonistic.

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Beta-galactosidases are enzymes that can be found in most living beings and in the plant kingdom its activity and genes have been detected in several tissues such as ripening fruits, developing leaves and flowers and storage tissues such as cotyledons. In plants, their activities are usually associated with the secondary metabolism or with oligosaccharide or polysaccharide degradation. Polysaccharide specific beta-galactosidases include beta-galactanases, which attack pectic polymers and beta-galactosidases that attack xyloglucans (XG). In the present work we purified an XG-specific beta-galactosidase (named hcbetagal) from cotyledons of developing seedlings of Hymenaea courbaril, a legume tree from the Neotropical region of the world. The enzyme has a molecular weight of 52-62 kDa and was shown to attack specifically xyloglucan oligosaccharides (XGOs) but not the polymer. It has a pH optimum between 3 and 4 and at this pH range the enzyme increases activity linearly up to 50 degrees C. Kinetic studies showed that hcbetagal is inhibited competitively by free galactose (K(i) = 3.7). The biochemical properties of hcbetagal as a whole suggest that it is involved in storage xyloglucan mobilisation during seedling development. Its high specificity towards XGOs, the low pH optimum and the fact that it is inhibited by its product (galactose) suggest that hcbetagal might be one of the biochemical control points in xyloglucan catabolism in vivo. A possible relationship with functional stability of the wall during cell death as cotyledons undergo senescence is discussed.

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Trichoderma reesei FTKO-39 grown at 35 degrees C for 5 d on wheat bran supplemented with MgCl2 and lactose as the carbon source produced two isozymes of beta-galactosidase: BGT I and BGT II. These isozymes were partially purified on a DEAE-Trisacryl column. Both BGT I and BGT II fractions exhibited optimum activity at 65 degrees C, but the pH optima were 4.0 and 6.5, respectively. The isozymes also showed similar thermal stability. However, BGT I was more stable than BGT II in a pH range of 3.0-10.0. At least two different beta-galactosidases are produced by T. reesei, as revealed by the two bands seen on a 6% polyacrylamide gel stained for activity.

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The purpose of this work was to optimize the beta-galactosidase production by Kluyveromyces lactis, applying the Surface Response Methodology (SRM) and using deproteinized whey as fermentation medium. An Orthogonal Central Compound Design (OCCD) was used without repetition, with four factors: temperature, pH, agitation speed and fermentation time. Then, enzyme activity (U/ml) as response variable was used. Thirty trials in twenty-five treatments, with six repetitions at the central point, were carried out, in a New Brunswick Bioflo 2000 fermentor with a volume of 2 liters. The deproteinized whey obtained by thermocoagulation was chemically analyzed. The results were: moisture 93.83%, total solids 6.17%, protein 0.44%, lactose 4.85%, acidity 0.43% and pH 4.58. The best conditions in the enzyme production were: temperature 30.3 degrees C, pH 4.68, agitation speed 191 r.p.m. and fermentation time 18.5 h. with an enzyme production of 8.3 U/ml. The degree of purification obtained was 7.4 times and the yield was 50.8%. The purified enzyme had an optimum temperature of 60 degrees C and a pH of 6.2. This work shows that the yeast Kluyveromyces lactis grown in deproteinized whey is able to produce the enzyme beta-galactosidase and SRM can be used in the fermentology processes, specifically in determining the best suitable operation conditions.

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The purpose of this work was to optimize the beta-galactosidase production by Kluyveromyces lactis, applying the Surface Response Methodology (SRM) and using deproteinized whey as fermentation medium. An Orthogonal Central Compound Design (OCCD) was used without repetition, with four factors: temperature, pH, agitation speed and fermentation time. Then, enzyme activity (U/ml) as response variable was used. Thirty trials in twenty-five treatments, with six repetitions at the central point, were carried out, in a New Brunswick Bioflo 2000 fermentor with a volume of 2 liters. The deproteinized whey obtained by thermocoagulation was chemically analyzed. The results were: moisture 93.83 per cent, total solids 6.17 per cent, protein 0.44 per cent, lactose 4.85 per cent, acidity 0.43 per cent and pH 4.58. The best conditions in the enzyme production were: temperature 30.3 degrees C, pH 4.68, agitation speed 191 r.p.m. and fermentation time 18.5 h. with an enzyme production of 8.3 U/ml. The degree of purification obtained was 7.4 times and the yield was 50.8 per cent. The purified enzyme had an optimum temperature of 60 degrees C and a pH of 6.2. This work shows that the yeast Kluyveromyces lactis grown in deproteinized whey is able to produce the enzyme beta-galactosidase and SRM can be used in the fermentology processes, specifically in determining the best suitable operation conditions.

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The midgut of the yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae) larvae has four beta-glycosidases. The properties of two of these enzymes (betaGly1 and betaGly2) have been described elsewhere. In this paper, the characterization of the other two glycosidases (betaGly3 and betaGly4) is described. BetaGly3 has one active site, hydrolyzes disaccharides, cellodextrins, synthetic substrates and beta-glucosides produced by plants. The enzyme is inhibited by amygdalin, cellotriose, cellotetraose and cellopentaose in high concentrations, probably due to transglycosylation. betaGly3 hydrolyzes beta 1,4-glycosidic linkages with a catalytic rate independent of the substrate polymerization degree (k(int)) of 11.9 s(-1). Its active site is formed by four subsites, where subsites +1 and -1 bind glucose residues with higher affinity than subsite +2. The main role of betaGly3 seems to be disaccharide hydrolysis. BetaGly4 is a beta-galactosidase, since it has highest activity against beta-galactosides. It can also hydrolyze fucosides, but not glucosides, and has Triton X-100 as a non-essential activator (K(a)=15 microM, pH 4.5). betaGly4 has two active sites that can hydrolyze p-nitrophenyl beta-galactoside (NPbetaGal). The one hydrolyzing NPbetaGal with more efficiency is also active against methylumbellipheryl beta-D-galactoside and lactose. The other active site hydrolyzes NPbetaFucoside and binds NPbetaGal weakly. BetaGly4 hydrolyzes hydrophobic substrates with high catalytical efficiency and is able to bind octyl-beta-thiogalactoside in its active site with high affinity. The betaGly4 physiological role is supposed to be the hydrolysis of galactolipids that are found in membranes from vegetal tissues. As the enzyme has a hydrophobic site where Triton X-100 can bind, it might be activated by membrane lipids, thus becoming fully active only at the surface of cell membranes.

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An alternative and fast method for the purification of an exo-beta-D-galactofuranosidase has been developed using a 4-aminophenyl 1-thio-beta-D-galactofuranoside affinity chromatography system and specific elution with 10 mM D-galactono-1,4-lactone in a salt gradient. A concentrated culture medium from Penicillium fellutanum was chromatographed on DEAE-Sepharose CL 6B followed by chromatography on the affinity column, yielding two separate peaks of enzyme activity when elution was performed with 10 mM D-galactono-1,4-lactone in a 100-500 mM NaCl salt gradient. Both peaks behaved as a single 70 kDa protein, as detected by SDS-PAGE. Antibodies elicited against a mixture of the single bands excised from the gel were capable of immunoprecipitating 0.2 units out of 0.26 total units of the enzyme from a crude extract. The glycoprotein nature of the exo-beta-D-galactofuranosidase was ascertained through binding to Concanavalin A-Sepharose as well as by specific reaction with Schiff reagent in Western blots. The purified enzyme has an optimum acidic pH (between 3 and 6), and Km and Vmax values of 0.311 mM and 17 mumol h-1 microgram-1 respectively, when 4-nitrophenyl beta-D-galactofuranoside was employed as the substrate.

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The intracellular enzyme beta-D-galactosidase provides interesting applications in the dairy industry, which are able to solve problems related to product processing, or can alleviate lactose intolerance in some populations. In order to obtain a technical enzyme, yeast cells of Kluyveromyces marxianus CDB 002 were disrupted by high pressure homogenization and an innovative chromatographic technique was tested for the recovery of beta-D-galactosidase. A STREAMLINE 25 column, containing 65 ml STREAMLINE-DEAE was equilibrated with 50 mM potassium phosphate buffer pH 7.5 at an upward flow of 250 cmh-1. 100-200 ml cell homogenate were applied onto the expanded gel. After unbound proteins and cellular debris were washed out, the bed was allowed to sediment and beta-D-galactosidase was eluted with a downward flow of 0.2 M NaCl in the same buffer. A 6-fold purification factor was achieved with 63% activity recovery, while removing cell debris at a single step, thus avoiding a centrifugation step. Concentration and volume of the applied sample affected purification and gel performance. The results presented show STREAMLINE-DEAE chromatography to be an interesting method for the production of beta-D-galactosidase as a technical enzyme, since it can also be applied on a large scale without much modification.

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Beta-galactosidase from rat epididymal fluid was purified by a combination of chromatographic techniques and precipitation with ammonium sulphate. Specific activity of the enzyme in the final precipitate was 18 times greater than in the original fluid, and it was practically free of N-acetyl-beta-D-glucosaminidase. A single major band was seen when the precipitate was analysed by sodium dodecylsulphate polyacrylamide gelectrophoresis (SDS-PAGE). The activity of the purified enzyme has an optimum at pH 4.5, and the temperature optimum is around 45 degrees C. The activity was inhibited by p-chloromercuribenzoic acid and ions such as Cd(II), Co(II), Cu(II) and Ag(I). Lactose does not appear to be a substrate for this enzyme.

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This study reports on the binding of beta-galactosidase obtained from different organs of the rat urogenital tract to membranes of these organs. Homologous and cross binding saturation assays indicated that: (1) high-affinity sites that recognize fructose-6-phosphate derivates (FPR) are present in spermatozoa from the rete testis, epididymal membranes and testes, although the latter may reflect binding to testicular spermatozoa; (2) the membranes of the other organs studied do not have FPR; (3) the FPR of the epididymis does not recognize enzymes purified from other organs of the reproductive tract. These results suggest that the FPR-binding system belongs to a peculiar transport route that permits maturing spermatozoa to acquire hydrolytic enzymes secreted by the epididymal epithelium. In the epididymis and seminal vesicles more than 50% of the enzymatic activity of beta-galactosidase was recovered in cytosol, suggesting that the enzyme is located mainly in the secretory fluid of these organs.

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The characterization and properties of a beta-galactanase and alpha- and beta-galactosidases as well as heparan sulfate and chondroitin sulfate degrading enzymes which appear during the 15 days of the embryonic development of the mollusc Pomacea sp. is reported. The beta-galactanase, which appears around day 7 of development, was separated from alpha- and beta-galactosidase which emerge at day 1 and 4 after oviposition, respectively. The galactanase seems to be responsible for the degradation of an acidic beta-galactan (which is also synthesized by the eggs around day 5) to galactose and di- and tri-galactosides. Heparan sulfate appears around day 10 of development together with a heparan sulfate endoglucuronidase responsible for the degradation of its N-acetylated region. An alpha-N-acetylglucosaminidase and a beta-glucuronidase which act upon the N-acetylated fragments formed from heparan sulfate emerge around day 4 of development. Chondroitin sulfate and a chondroitin sulfate sulfatase emerge around day 9 of development whereas a beta-N-acetylgalactosaminidase and the beta beta-galactan, heparan and chondroitin sulfate, respectively. The possible role of these elements in the migration of mesenchymal cells, in the processes of cell-cell recognition and control of cell growth is discussed.

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Se presenta un procedimiento de obtención de ß-galactosidasa recombinante en Escherichia coli con una pureza superior al 95 % basado en dos pasos de purificación y solo uno de ellos cromatográficos. Se combinaron en el trabajo la precipitación salina y la cromatografía de interacción hidrofóbica en Fractogel TSK butilo 650 M, alcanzándose en esta última una alta resolución mediante el ajuste efectivo de los parámetros determinantes en esta operación

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La enzima ß-galactosidasa producida por vía recombinante en E. Coli fue purificada por cromatografía de intercambio iónico y filtración por gel, lográndose una preparación de enzima de más del 95 % de pureza. Su capacidad como enzima marcadora en inmunoensayo enzimático sobre fase sólida (ELISA), fue probada comparándose con peroxidasa, la cual ha sido ampliamente usada en estos ensayos. Se realizaron conjugados con anticuerpo monoclonal anti-rotavirus para un sistema de detección de rotavirus, utilizando el agente heterobifuncional SPDP. Se obtuvieron niveles similares de sensibilidad para los conjugados realizados con peroxidasa y ß-galactosidasa; igualmente no se observaron diferencias significativas en el parámetro unión específica/unión no específica. En el presente trabajo mostramos los resultados obtenidos en la purificación de la enzima, su seguimiento por actividad enzimática y su uso como enzima marcadora en inmunoensayo enzimático

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