The Experts below are selected from a list of 24 Experts worldwide ranked by ideXlab platform
Byunggee Kim - One of the best experts on this subject based on the ideXlab platform.
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using tyrosinase as a Monophenol Monooxygenase a combined strategy for effective inhibition of melanin formation
Biotechnology and Bioengineering, 2016Co-Authors: Sanghyuk Lee, Kiheon Baek, Jueun Lee, Byunggee KimAbstract:Tyrosinase is a binuclear copper-containing metalloprotein that leads the fast and regio-selective o-hydroxylation of Monophenols to o-diphenols. However, the subsequent second oxidation to produce o-quinones, i.e., melanin precursors, from the o-diphenols has restricted its use to the production of functional o-diphenol derivatives. Herein, we present a combined strategy for the effective inhibition of melanin formation in tyrosinase reaction, which allows the use of tyrosinase as a Monophenol Monooxygenase. The o-diphenolic products were protected from being oxidized in the tyrosinase reaction by borate ions and L-ascorbic acid (LAA). Borate-o-diphenol complexes were favorable formed at high pH and consequentially protected the o-diphenolic products from the catecholase activity of tyrosinase. LAA not only directly reduced the byproduct, o-quinones, into o-diphenols but also assisted the completion of the tyrosinase reaction cycle by removing a hydroxyl group attached to the copper metal cluster at the active site of the met-form tyrosinase. The regio-selective o-hydroxylation of 7,4'-dihydroxyisoflavone (daidzein) to produce 7,3',4'-trihydroxyisoflavone (3'-ODI) was successfully carried out by whole E. coli cell biotransformation with heterologously expressed tyrosinase from Bacillus megaterium. The yield of this o-hydroxylation of 5 mM daidzein in one-pot 400 mL reaction was ca. 100% in 90 min and the productivity was 16.3 mg 3'-ODI · L(-1) · h(-1) · DCW mg(-1), which is considerably higher than that of other Monooxygenases. The method effectively abolished melanin synthesis, so that the o-diphenolic product remained stable without enzyme inactivation. Other Monophenolic phytochemicals such as resveratrol and genistein could be subjected to the same strategy. After 1 h, 1 mM of genistein and resveratrol were both converted to orobol and piceatannol, respectively, with ca. 95% conversion yield. These results support the strong potential of tyrosinase as a Monooxygenase for regio-selective o-hydroxylation of various Monophenolic compounds.
Sanghyuk Lee - One of the best experts on this subject based on the ideXlab platform.
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using tyrosinase as a Monophenol Monooxygenase a combined strategy for effective inhibition of melanin formation
Biotechnology and Bioengineering, 2016Co-Authors: Sanghyuk Lee, Kiheon Baek, Jueun Lee, Byunggee KimAbstract:Tyrosinase is a binuclear copper-containing metalloprotein that leads the fast and regio-selective o-hydroxylation of Monophenols to o-diphenols. However, the subsequent second oxidation to produce o-quinones, i.e., melanin precursors, from the o-diphenols has restricted its use to the production of functional o-diphenol derivatives. Herein, we present a combined strategy for the effective inhibition of melanin formation in tyrosinase reaction, which allows the use of tyrosinase as a Monophenol Monooxygenase. The o-diphenolic products were protected from being oxidized in the tyrosinase reaction by borate ions and L-ascorbic acid (LAA). Borate-o-diphenol complexes were favorable formed at high pH and consequentially protected the o-diphenolic products from the catecholase activity of tyrosinase. LAA not only directly reduced the byproduct, o-quinones, into o-diphenols but also assisted the completion of the tyrosinase reaction cycle by removing a hydroxyl group attached to the copper metal cluster at the active site of the met-form tyrosinase. The regio-selective o-hydroxylation of 7,4'-dihydroxyisoflavone (daidzein) to produce 7,3',4'-trihydroxyisoflavone (3'-ODI) was successfully carried out by whole E. coli cell biotransformation with heterologously expressed tyrosinase from Bacillus megaterium. The yield of this o-hydroxylation of 5 mM daidzein in one-pot 400 mL reaction was ca. 100% in 90 min and the productivity was 16.3 mg 3'-ODI · L(-1) · h(-1) · DCW mg(-1), which is considerably higher than that of other Monooxygenases. The method effectively abolished melanin synthesis, so that the o-diphenolic product remained stable without enzyme inactivation. Other Monophenolic phytochemicals such as resveratrol and genistein could be subjected to the same strategy. After 1 h, 1 mM of genistein and resveratrol were both converted to orobol and piceatannol, respectively, with ca. 95% conversion yield. These results support the strong potential of tyrosinase as a Monooxygenase for regio-selective o-hydroxylation of various Monophenolic compounds.
Jueun Lee - One of the best experts on this subject based on the ideXlab platform.
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using tyrosinase as a Monophenol Monooxygenase a combined strategy for effective inhibition of melanin formation
Biotechnology and Bioengineering, 2016Co-Authors: Sanghyuk Lee, Kiheon Baek, Jueun Lee, Byunggee KimAbstract:Tyrosinase is a binuclear copper-containing metalloprotein that leads the fast and regio-selective o-hydroxylation of Monophenols to o-diphenols. However, the subsequent second oxidation to produce o-quinones, i.e., melanin precursors, from the o-diphenols has restricted its use to the production of functional o-diphenol derivatives. Herein, we present a combined strategy for the effective inhibition of melanin formation in tyrosinase reaction, which allows the use of tyrosinase as a Monophenol Monooxygenase. The o-diphenolic products were protected from being oxidized in the tyrosinase reaction by borate ions and L-ascorbic acid (LAA). Borate-o-diphenol complexes were favorable formed at high pH and consequentially protected the o-diphenolic products from the catecholase activity of tyrosinase. LAA not only directly reduced the byproduct, o-quinones, into o-diphenols but also assisted the completion of the tyrosinase reaction cycle by removing a hydroxyl group attached to the copper metal cluster at the active site of the met-form tyrosinase. The regio-selective o-hydroxylation of 7,4'-dihydroxyisoflavone (daidzein) to produce 7,3',4'-trihydroxyisoflavone (3'-ODI) was successfully carried out by whole E. coli cell biotransformation with heterologously expressed tyrosinase from Bacillus megaterium. The yield of this o-hydroxylation of 5 mM daidzein in one-pot 400 mL reaction was ca. 100% in 90 min and the productivity was 16.3 mg 3'-ODI · L(-1) · h(-1) · DCW mg(-1), which is considerably higher than that of other Monooxygenases. The method effectively abolished melanin synthesis, so that the o-diphenolic product remained stable without enzyme inactivation. Other Monophenolic phytochemicals such as resveratrol and genistein could be subjected to the same strategy. After 1 h, 1 mM of genistein and resveratrol were both converted to orobol and piceatannol, respectively, with ca. 95% conversion yield. These results support the strong potential of tyrosinase as a Monooxygenase for regio-selective o-hydroxylation of various Monophenolic compounds.
Kiheon Baek - One of the best experts on this subject based on the ideXlab platform.
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using tyrosinase as a Monophenol Monooxygenase a combined strategy for effective inhibition of melanin formation
Biotechnology and Bioengineering, 2016Co-Authors: Sanghyuk Lee, Kiheon Baek, Jueun Lee, Byunggee KimAbstract:Tyrosinase is a binuclear copper-containing metalloprotein that leads the fast and regio-selective o-hydroxylation of Monophenols to o-diphenols. However, the subsequent second oxidation to produce o-quinones, i.e., melanin precursors, from the o-diphenols has restricted its use to the production of functional o-diphenol derivatives. Herein, we present a combined strategy for the effective inhibition of melanin formation in tyrosinase reaction, which allows the use of tyrosinase as a Monophenol Monooxygenase. The o-diphenolic products were protected from being oxidized in the tyrosinase reaction by borate ions and L-ascorbic acid (LAA). Borate-o-diphenol complexes were favorable formed at high pH and consequentially protected the o-diphenolic products from the catecholase activity of tyrosinase. LAA not only directly reduced the byproduct, o-quinones, into o-diphenols but also assisted the completion of the tyrosinase reaction cycle by removing a hydroxyl group attached to the copper metal cluster at the active site of the met-form tyrosinase. The regio-selective o-hydroxylation of 7,4'-dihydroxyisoflavone (daidzein) to produce 7,3',4'-trihydroxyisoflavone (3'-ODI) was successfully carried out by whole E. coli cell biotransformation with heterologously expressed tyrosinase from Bacillus megaterium. The yield of this o-hydroxylation of 5 mM daidzein in one-pot 400 mL reaction was ca. 100% in 90 min and the productivity was 16.3 mg 3'-ODI · L(-1) · h(-1) · DCW mg(-1), which is considerably higher than that of other Monooxygenases. The method effectively abolished melanin synthesis, so that the o-diphenolic product remained stable without enzyme inactivation. Other Monophenolic phytochemicals such as resveratrol and genistein could be subjected to the same strategy. After 1 h, 1 mM of genistein and resveratrol were both converted to orobol and piceatannol, respectively, with ca. 95% conversion yield. These results support the strong potential of tyrosinase as a Monooxygenase for regio-selective o-hydroxylation of various Monophenolic compounds.
Linsheng Song - One of the best experts on this subject based on the ideXlab platform.
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the phenoloxidase activity and antibacterial function of a tyrosinase from scallop chlamys farreri
Fish & Shellfish Immunology, 2012Co-Authors: Zhi Zhou, Mengqiang Wang, Lingling Wang, Leilei Wang, Xiaowei Shi, Feng Yue, Rui Liu, Linsheng SongAbstract:Abstract Tyrosinase (TYR), also known as Monophenol Monooxygenase, is a ubiquitous binuclear copper-containing enzyme which catalyzes the hydroxylation of phenols to catechols and the oxidation of catechols to quinones. In the present study, the cDNA of a tyrosinase (CfTYR) was identified from scallop Chlamys farreri , which encoded a polypeptide of 486 amino acids. The CfTYR mRNA transcripts were expressed in all the tested tissues, including haemocytes, adductor muscle, kidney, hepatopancreas, gill, gonad and mantle, with the highest level in mantle. The expression level of CfTYR mRNA in haemocytes decreased significantly during 3–6 h after LPS stimulation, and reached the lowest level at 6 h (0.05-fold, P P > 0.05), and reached the highest level at 24 h (2.91-fold, P −1 respectively, but it decreased to 10.82 U mg −1 and even undetectable level after CfTYR activity was inhibited. Furthermore, the antibacterial activity of haemolymph against Escherichia coli was also increased significantly at 3 h after LPS stimulation, but it decreased significantly when the haemolymph was treated by TYR inhibitor. The recombinant protein of the mature CfTYR peptide expressed in the in vitro Glycoprotein Expression Kit displayed phenoloxidase activity of 64.36 ± 5.51 U mg −1 in the present of trypsinase and Cu 2+ . These results collectively suggested that CfTYR was a homologue of tyrosinase in scallop C . farreri with the copper-dependence phenoloxidase activity, and it could be induced after immune stimulation and mediate immune response for the elimination of invasive pathogens in scallop.