Characterisation of tyrosinase immobilised onto spacer-arm attached glycidyl methacrylate-based reactive microbeads

Arıca, M. Yakup; Bayramoğlu, Gülay; Bıçak, Niyazi

doi:10.1016/j.procbio.2003.09.030

Cited by 85 publications

(45 citation statements)

References 35 publications

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“…5). The calculated K m values of PPOs from APs do not differ significantly from each other, but they are higher than the K m values of 0.21 mM [45] and 0.25 mM [46] for whole mushroom PPO, and lower than the K m of 0.58 mM [37] for commercial mushroom PPO.…”

Section: Kinetic Propertiescontrasting

confidence: 60%

“…2, the activities of enzymes from different APs effected similarly from temperature change and showed maximal activity at 40 8C. The temperature-monophenolase activity profile of enzymes observed in this study differs from those of partially purified mushroom PPO [23,26] and commercial mushroom PPO [37], which gave sharp peaks at 20 and 30 8C, respectively. In the temperature range studied, the activation energies (E a ) calculated from Arrhenius plot were 31.4 and 29.4 kJ/mol for the monophenolase activity of PPO from AP-3 and AP-8, respectively.…”

Section: Effect Of Temperaturementioning

confidence: 49%

“…Ikehata and Nicell [18] found that the monophenolase activity of commercial mushroom PPO is heat labile and lost 90% of its initial activity at 50 8C after 38 min incubation (at pH 7.0). In contrast, Arıca et al [37] reported that the commercial mushroom PPO maintained almost 95% and 70% of its monophenolase activity after 30 min heating at 50 and 60 8C, respectively (at pH 6.5). These reports showing the diversity of the thermal stability of mushroom PPO suggest a moderate heat stability for monophenolase activity of mushroom stem PPO.…”

Section: Thermal Stabilitymentioning

confidence: 88%

“…However, the commercial enzyme used by these workers was more active at pH 5.0. Arıca et al [37] also reported that at pH 4.0, the commercial mushroom PPO showed 30% of its monophenolase activity observed at optimum pH. Thus, it seems that the commercial mushroom PPO is more active in the acidic region than the mushroom stem PPO.…”

Section: Effect Of Phmentioning

confidence: 94%

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Partial purification and kinetic characterization of mushroom stem polyphenoloxidase and determination of its storage stability in different lyophilized forms

Şimşek¹,

Yemenicioğlu²

2007

Process Biochemistry

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Monophenolase (1011 AE 626 U/g AP) and diphenolase activities (5163 AE 3059 U/g AP) of PPO in acetone powders (APs) of different mushroom stems varied considerably. However, the limited variation of average dipenolase (L-DOPA) to monophenolase (L-tyrosine) activity ratio (5.4 AE 0.7) in crude extracts showed the homogeneity of PPO from different mushroom stems. The change in extraction material or partial purification method (ammonium sulfate or acetone precipitation) did not affect the temperature stability, temperature and pH dependency and K m of monophenolase activity considerably. However, some changes were observed in pH stability and substrate specificity of PPO in different parties of mushroom stems. The most important aspects of mushroom stem PPO are its lower diphenolase to monophenolase activity ratio than mushroom cap PPO, low temperature dependency of activity between 25 and 40 8C (E a = 30 kJ/mol), broad optimum pH between 6 and 8, but lack of activity pH 5, and ability to use phloridzin as substrate. The mushroom stem PPOs partially purified and lyophilized by using sucrose, dextran or alginate showed moderate to high stability at À18 8C for 6-6.5 months. Thus, the mushroom stems obtained as a waste material during mushroom processing may be used as a more homogenous source than whole mushrooms to obtain PPO used for different industrial, clinical or research purposes. #

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Section: Kinetic Propertiescontrasting

confidence: 60%

Section: Effect Of Temperaturementioning

confidence: 49%

Section: Thermal Stabilitymentioning

confidence: 88%

Section: Effect Of Phmentioning

confidence: 94%

See 2 more Smart Citations

Partial purification and kinetic characterization of mushroom stem polyphenoloxidase and determination of its storage stability in different lyophilized forms

Şimşek¹,

Yemenicioğlu²

2007

Process Biochemistry

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“…It is inert in normal biological reactions. It is resistant to degradation, is not absorbed by the body, can be sterilized with heat, and can be prepared in many different shapes and forms [4][5][6]. The other hydrogel has the medical importance is polyacrylamide.…”

Section: Introductionmentioning

confidence: 99%

Preparatıon and Application of Biocompatible Carrier Implant to be Used in the Controlled Acquisition of Digoxin

Kayalik

Çetin

2016

Journal of the Turkish Chemical Society, Section A: Chemistry

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Abstract:In this study, a persistent system is aimed to be established which contributes to slow basal digoxin release in the treatment of cardiac failure. Poly(2-hydroxyethylmetacrylate-methylmetacrylate) (p(HEMA-MMA) copolymer that can swell by taking on water is prepared in cylindirical form by UV photopolymerization method for the controlled-release of digoxin and effective hydrogel implant formulation. A batch of p(HEMA-MMA) composition is prepared in different monomer ratios. Biocompatibility is improved by adding PEO, PEG and serum albumin to the structures of p(HEMA-MMA), respectively. Scanning electron microscope (SEM) studies are carried out for the surface structure of the prepared carrier implant material and differential scanning calorimetry (DSC) studies for the thermal stability analysis. Swelling behaviors are investigated by transferring solvent molecules to the hydrogels. Digoxin release kinetics are evaluated by applying three different accumulative digoxin doses (100, 250 and 500 U/mL) in the persistent flow release system containing physiological phosphate. Power law, level-zero, and Higuchi model equations are utilized so as to evaluate the release mechanism of digoxin. The most suitable results are acquired from the composition whose HEMA:MMA monomer ratio is 1:0.5 (v/v) in drug accumulation and release studies. It is observed from the SEM image that the carrier implant in the structure of the acquired hydrogel has a smooth surface. According to DSC results, it is seen that thermal stability decreases in the event that MMA comonomer is added to the structure of the pHEMA hydrogel. Balance water amount within the physiological phosphate buffer of the p(HEMA-MMA) copolymer is observed to be less than the pHEMA. Digoxin release loaded to carrier implants by different ratios takes a long-term period as expected. It is decided that the formulation established in the study can be successfully applied for the basal digoxin level over four weeks in the treatment of chronic cardiac failure.

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Covalent Enzyme Immobilization

Cao¹

2005

Carrier‐bound Immobilized Enzymes

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Characterisation of tyrosinase immobilised onto spacer-arm attached glycidyl methacrylate-based reactive microbeads

Cited by 85 publications

References 35 publications

Partial purification and kinetic characterization of mushroom stem polyphenoloxidase and determination of its storage stability in different lyophilized forms

Partial purification and kinetic characterization of mushroom stem polyphenoloxidase and determination of its storage stability in different lyophilized forms

Preparatıon and Application of Biocompatible Carrier Implant to be Used in the Controlled Acquisition of Digoxin

Covalent Enzyme Immobilization

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