Abstract:A laccase from the aquatic ascomycete Phoma sp. UHH 5-1-03 (DSM 22425) was purified upon hydrophobic interaction and size exclusion chromatography (SEC). Mass spectrometric analysis of the laccase monomer yielded a molecular mass of 75.6 kDa. The enzyme possesses an unusual alkaline isoelectric point above 8.3. The Phoma sp. laccase undergoes pH-dependent dimerisation, with the dimer ( approximately 150 kDa, as assessed by SEC) predominating in a pH range of 5.0 to 8.0. The enzyme oxidises common laccase subst… Show more
“…Comparing to other studies, the results obtained were quite encouraging. However, Junghanns et al (2009) reported 117-fold purification of laccase enzyme with very low yield of 0.95 %.…”
Section: Resultsmentioning
confidence: 99%
“…The relative molecular mass of laccase purified from Lentinula edodes and Phoma sp. reported to be 58.5 and 75.6 kDa, respectively (Junghanns et al 2009; Ulrich et al 2005). Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Laccase from Phoma sp. UHH 5-1-03 showed optimum pH 5.0 when guaiacol was used as a substrate (Junghanns et al 2009). A gradual decrease in the oxidation rate of various substrates was observed at higher pH, which may be due to ionization of critical amino acids (Asp and Glu), indicating that the enzyme was inactive at higher pH (Salony et al 2006).…”
A native isolate of Pleurotus ostreatus HP-1 (Genbank Accession No. EU420068) was found to have an excellent laccase producing ability. The extracellular laccase was purified to electrophoretic homogeneity from copper sulphate induced solid-state fermentation medium by ammonium sulphate precipitation and ion-exchange chromatography. The enzyme was determined to be monomeric protein with an apparent molecular mass of 68,420 kDa, and an isoelectric point (pI) of 3.5. The inductively coupled plasma spectroscopy showed a presence of iron, zinc and copper in the purified enzyme. The absorption spectrum in the range of 200–700 nm showed the maximum absorption at 610 nm characteristic of fungal laccase and corresponding to the presence of type I copper atom. The laccase was stable at different temperatures up to 70 °C and retained 61 % activity at 50 °C. The enzyme reaction was inhibited by cysteine; sodium azide and EDTA. The enzyme oxidized various known laccase substrates, its lowest Km value being for ortho-dianisidine and highest Kcat and Kcat/Km for ABTS. The purified laccase exhibited different pH optima for different substrates. The N-terminal sequence did not show any similarity with N-terminal sequence of other species of genera Pleurotus.
“…Comparing to other studies, the results obtained were quite encouraging. However, Junghanns et al (2009) reported 117-fold purification of laccase enzyme with very low yield of 0.95 %.…”
Section: Resultsmentioning
confidence: 99%
“…The relative molecular mass of laccase purified from Lentinula edodes and Phoma sp. reported to be 58.5 and 75.6 kDa, respectively (Junghanns et al 2009; Ulrich et al 2005). Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Laccase from Phoma sp. UHH 5-1-03 showed optimum pH 5.0 when guaiacol was used as a substrate (Junghanns et al 2009). A gradual decrease in the oxidation rate of various substrates was observed at higher pH, which may be due to ionization of critical amino acids (Asp and Glu), indicating that the enzyme was inactive at higher pH (Salony et al 2006).…”
A native isolate of Pleurotus ostreatus HP-1 (Genbank Accession No. EU420068) was found to have an excellent laccase producing ability. The extracellular laccase was purified to electrophoretic homogeneity from copper sulphate induced solid-state fermentation medium by ammonium sulphate precipitation and ion-exchange chromatography. The enzyme was determined to be monomeric protein with an apparent molecular mass of 68,420 kDa, and an isoelectric point (pI) of 3.5. The inductively coupled plasma spectroscopy showed a presence of iron, zinc and copper in the purified enzyme. The absorption spectrum in the range of 200–700 nm showed the maximum absorption at 610 nm characteristic of fungal laccase and corresponding to the presence of type I copper atom. The laccase was stable at different temperatures up to 70 °C and retained 61 % activity at 50 °C. The enzyme reaction was inhibited by cysteine; sodium azide and EDTA. The enzyme oxidized various known laccase substrates, its lowest Km value being for ortho-dianisidine and highest Kcat and Kcat/Km for ABTS. The purified laccase exhibited different pH optima for different substrates. The N-terminal sequence did not show any similarity with N-terminal sequence of other species of genera Pleurotus.
“…This is the case for T. villosa [106] and Phellinus ribis [107], for the phytopathogenic ascomycetes Rhizoctonia solani [108] and Gaeumannomyces graminis [109], and for the aquatic ascomycete Phoma sp. UHH 5-1-03 [110]. The latter enzyme undergoes a pH-dependent dimerization, with the dimer predominating in a pH range of 5.0-8.0.…”
Laccases (benzenediol:oxygen oxidoreductases, EC 1.10.3.2) are blue multicopper oxidases that catalyze the oxidation of an array of aromatic substrates concomitantly with the reduction of molecular oxygen to water. In fungi, laccases carry out a variety of physiological roles during their life cycle. These enzymes are being increasingly evaluated for a variety of biotechnological applications due to their broad substrate range. In this review, the most recent studies on laccase structural features and catalytic mechanisms along with analyses of their expression are reported and examined with the aim of contributing to the discussion on their structure-function relationships. Attention has also been paid to the properties of enzymes endowed with unique characteristics and to fungal laccase multigene families and their organization.
“…The adsorption pH tested range (25 mM citric acid/50 mM Na 2 HPO 4 buffer, modification after [14]) was 7.2-9.1 and chosen because laccases are usually stable at neutral to slightly alkaline pHs [15,16]. Ionic strength of laccase solution was adjusted by addition of sodium chloride after the laccase solution and the buffers were mixed.…”
Section: Laccase-biocatalyst Design and Formulationmentioning
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