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Enzyme and Microbial Technology | 1998

The Induction and Characterization of Phytase and Beyond

Bing-Lan Liu; Amjad Rafiq; Yew-Min Tzeng; Abdul Rob

Abstract The hydrolysis of phytic acid, the principal storage form of phosphorus in seeds and pollen, to myo-inositol and phosphoric acid is a very important metabolic process in many biological systems. This dephosphorylation of free or bound inositol phosphate is believed to be mainly affected by phytase. Generally, phytase behaves like a monomeric protein of a molecular mass of approximately 40–200 kDa and shows a broad substrate specificity with optimal degradation of phytate occurring around pH 4.5–6.0 and a temperature at 45–60°C. Furthermore, it is found that the Aspergillus ficuum phytase consists of 594 amino acid residues and the secondary structure contains 17.3% α-helixes, 29% β-sheet, 32.6% turns, and 24.7% coils. The N-linked mannose and galactose of intact phytase from A. ficuum account for 27.3% of the molecular weight. This implies that the enzyme is a glycoprotein. Recently, the crystal structure of this phytase has been determined at 2.5 A resolution. In this review, the properties of various phytases are summarized and the digestion of phytate by phytase and its products are also discussed.


Enzyme and Microbial Technology | 1999

Optimization of extracellular lignocellulolytic enzyme production by a thermophilic actinomycete Thermomonospora fusca BD25

Müni̇r Tuncer; Andrew S. Ball; Abdul Rob; Michael T. Wilson

Abstract The production of extracellular lignocellulose-degrading enzymes, endo-1,4-β-xylanase, endo-1,4-β-glucanase and peroxidase during the growth of Thermomonospora fusca BD25 in basal salts-yeast extract medium containing different carbon sources was studied. The effect of a number of environmental parameters (e.g. dissolved oxygen concentration, pH and temperature) was also investigated using batch and automated bioreactor conditions. The highest enzyme activities were generally obtained after 48–96 h of incubation at 50°C in a basal salts medium containing either 0.6% or 0.8% (w/v) oat spelt xylan and 0.6% (w/v) yeast extract corresponding to C:N ratios of 4 to 1 and 5.3 to 1, respectively. A comparison of enzyme activities revealed that the activity of endo-1,4-β-xylanase (2.68 U ml −1 ) was greater than those of the other enzyme activities (0.24 U ml −1 ; 12.08 mU ml −1 ; 19.62 mU ml −1 and 2 mU ml −1 ) for endo-1,4-β-glucanase, peroxidase, β-xylosidase and α- l -arabinofuranosidase, respectively. The high levels of enzyme production achieved under bioreactor conditions, coupled with the temperature stability and the activity over a broad pH range of these enzymes signify the suitability for industrial applications such as pulp and paper production. Cell-free enzyme preparations from T. fusca BD25 were capable of releasing both sugar and aromatic compounds during incubation with both ball-milled wheat straw and eucalyptus paper pulp.


Applied Biochemistry and Biotechnology | 1997

Production and partial characterization of extracellular peroxidases produced bystreptomyces avermitilis UAH30

Abdul Rob; Manuel Hernández; Andrew S. Ball; Munir Tuncer; María E. Arias; Michael T. Wilson

The effect of a number of environmental parameters (pH, temperature, carbon and nitrogen ratio of nutrient) on the production of extracellular peroxidase enzymes byStreptomyces avermitilis UAH30 was examined. Maximum specific peroxidase activity (0.12 U/mg of protein) was obtained after 72 hours of 1 incubation at 45‡C in a minimal salt medium (pH 7.5) containing 0.6% (w/v) yeast extract and 0.6% (w/v) xylan corresponding to a C:N ratio of 4 to 1. A study of the effect of incubation on peroxidase activity showed that the enzyme was stable and active for at least one hour after incubation at 50‡C while at higher temperatures the stability and activity of the peroxidase was reduced such that at 60‡C the peroxidase activity has a half life of 20 min while at 80‡C the half life was reduced to 5 min. The activation energy for deactivation as a result of thermal denaturation of the enzyme was calculated to be 80 ±7 kJ/mol. The optimum pH for the activity occurred between a pH range of 6.5–8.5 with pKa1 and pKa2 of 5.1 ±0.1 and 9.7 ±0.1, respectively. The Km and Vmax for the peroxidase activity were determined to be 1.45 mM and 0.31 unit per mg protein respectively using 2,4dicholorophenol (2,4-DCP) as a substrate. Characterization of the peroxidase activity revealed activity against L,3–4 dihydroxyphenylalanine and guaiacol, while no inhibition of peroxidase activity could be detected with the haem inhibitors such as potassium cyanide and sodium azide, suggesting the lack of haem component in the tertiary structure. Aspects of using the crude peroxidase preparation in the pulp and paper industry are discussed.


Enzyme and Microbial Technology | 2001

Dechlorination of chlorophenols using extracellular peroxidases produced by streptomyces albus ATCC 3005.

Vasileios T Antonopoulos; Abdul Rob; Andrew S. Ball; Michael T. Wilson

Streptomyces albus ATCC 3005 was found to produce higher levels of extracellular peroxidase activity (3.420 U mg(-1)) than previously reported for any other actinomycete. Maximum peroxidase activity was obtained after 72 h of incubation at a temperature of 30 degrees C in a liquid medium (pH 7.6) containing (in w/v) 0.8% to 0.9% oat spelts xylan and 0.6% yeast extract, corresponding to a C:N ratio of around 8.4:1. Characterization of the peroxidases revealed that the optimal temperature for peroxidase activity, using the standard 2,4-dichlorophenol (2,4-DCP) assay was 53 degrees C, when the enzyme reaction was performed at pH 7.2. A study of the effect of temperature on the stability of peroxidase over time, showed that the enzyme was stable at 40 degrees C, with a half-life of 224 min, while at higher temperatures the stability and activity was reduced such that at 50 degrees C and 70 degrees C the half-life of the enzyme was 50 min and 9 min respectively. The optimum pH for the activity of the enzyme occurred between pH 8.1 and 10.4. In terms of substrate specificity, the peroxidase was able to catalyze a broad range of substrates including 2,4-DCP, L-3,4-dihydroxyphenylalanine (L-DOPA), 2,4,5-trichlorophenol and other chlorophenols in the presence of hydrogen peroxide. Ion exchange chromatography was used to confirm that the enzyme was able to release chloride ions from a range of chlorophenols.


Biochimica et Biophysica Acta | 1999

The electron paramagnetic resonance characterisation of a copper-containing extracellular peroxidase from Thermomonospora fusca BD25.

Dimitri A. Svistunenko; Abdul Rob; Andrew S. Ball; Jaume Torres; Martyn C.R. Symons; Michael T. Wilson; Chris E. Cooper

The actinomycete Thermomonospora fusca BD25 contains a peroxidase with a high activity over a broad range of temperature and pH and a high stability against denaturing agents. Unusually this peroxidase (PO) is a non-haem enzyme. As prepared PO is characterised by two electron paramagnetic resonance (EPR) signals, detected at liquid helium temperature, a free radical signal (g=2.0045) and a broad signal at g=2.056. The peroxidase activity of the purified enzyme was assayed using H(2)O(2) and 2,4-dichlorophenol (DCP). The intensity of the free radical EPR signal correlated with the peroxidase activity in a variety of enzyme preparations. Furthermore, when DCP and H(2)O(2) were added to PO a significant increase of both the free radical signal and the broad signal at g=2.056 was observed. We associate the increase of the broad signal with the oxidation of the preparation since a similar increase can be achieved by the addition of ferricyanide. The high intensity of the broad signal in the ferricyanide treated PO allowed us to deconvolute the signal into several components using the difference in their relaxation characteristics: two distinct copper signals were detected, one of which was similar to a type 2 centre. Furthermore a symmetrical singlet was detected at g=2.059, consistent with the presence of an iron complex with a high degree of symmetry and weakly coordinated ligands.


Biotechnology and Applied Biochemistry | 1996

Thermostable novel non-haem extracellular glycosylated peroxidase from Thermomonospora fusca BD25

Abdul Rob; Andrew S. Ball; Munir Tuncer; Michael T. Wilson


Journal of Chemical Education | 1997

Novel Applications of Peroxidase

Abdul Rob; Andrew S. Ball; Munir Tuncer; Michael T. Wilson


Biochemical Society Transactions | 1997

The detection and quantification of novel non-haem extracellular glycosylated peroxidases produced by the thermophilic actinomycete Thermomonospora fusca BD25 by means of PAGE-zymogram

Abdul Rob; Andrew S. Ball; Munir Tuncer; Michael T. Wilson


Biochemical Society Transactions | 1995

Isolation and characterisation of a novel non-haem extracellular peroxidase produced by the thermophilic actinomycete Thermonospora fusca BD25.

Abdul Rob; Andrew S. Ball; Munir Tuncer; Michael T. Wilson


Biochemical Society Transactions | 1996

Production of extracellular lignocellulose degrading enzymes by Thermomonospora fusca BD25.

Munir Tuncer; Abdul Rob; Andrew S. Ball; Michael T. Wilson

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