scholarly journals Polyphenol-Hydroxylating Tyrosinase Activity under Acidic pH Enables Efficient Synthesis of Plant Catechols and Gallols

2021 ◽  
Vol 9 (9) ◽  
pp. 1866
Author(s):  
Hanbit Song ◽  
Pyung-Gang Lee ◽  
Hyun Kim ◽  
Uk-Jae Lee ◽  
Sang-Hyuk Lee ◽  
...  

Tyrosinase is generally known as a melanin-forming enzyme, facilitating monooxygenation of phenols, oxidation of catechols into quinones, and finally generating biological melanin. As a homologous form of tyrosinase in plants, plant polyphenol oxidases perform the same oxidation reactions specifically toward plant polyphenols. Recent studies reported synthetic strategies for large scale preparation of hydroxylated plant polyphenols, using bacterial tyrosinases rather than plant polyphenol oxidase or other monooxygenases, by leveraging its robust monophenolase activity and broad substrate specificity. Herein, we report a novel synthesis of functional plant polyphenols, especially quercetin and myricetin from kaempferol, using screened bacterial tyrosinases. The critical bottleneck of the biocatalysis was identified as instability of the catechol and gallol under neutral and basic conditions. To overcome such instability of the products, the tyrosinase reaction proceeded under acidic conditions. Under mild acidic conditions supplemented with reducing agents, a bacterial tyrosinase from Bacillus megaterium (BmTy) displayed efficient consecutive two-step monophenolase activities producing quercetin and myricetin from kaempferol. Furthermore, the broad substrate specificity of BmTy toward diverse polyphenols enabled us to achieve the first biosynthesis of tricetin and 3′-hydroxyeriodictyol from apigenin and naringenin, respectively. These results suggest that microbial tyrosinase is a useful biocatalyst to prepare plant polyphenolic catechols and gallols with high productivity, which were hardly achieved by using other monooxygenases such as cytochrome P450s.

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 467
Author(s):  
Thandanani Ndlovu ◽  
Sidy Ba ◽  
Soraya P Malinga

Over the past two decades, phenol oxidases, particularly laccases and tyrosinases, have been extensively used for the removal of numerous pollutants in wastewaters due to their broad substrate specificity and their ability to use readily accessible molecular oxygen as the essential cofactor. As for other enzymes, immobilisation of laccases and tyrosinases has been shown to improve the performance and efficiency of the biocatalysts in solution. Several reviews have addressed the enzyme immobilisation techniques and the application of phenol oxidases to decontaminate wastewaters. This paper offers an overview of the recent publications, mainly from 2012 onwards, on the various immobilisation techniques applied to laccases and tyrosinases to induce and/or increase the performance of the biocatalysts. In this paper, the emphasis is on the efficiencies achieved, in terms of structural modifications, stability and resistance to extreme conditions (pH, temperature, inhibitors, etc.), reactivity, reusability, and broad substrate specificity, particularly for application in bioremediation processes. The advantages and disadvantages of several enzyme immobilisation techniques are also discussed. The relevance and effectiveness of the immobilisation techniques with respect to wastewater decontamination are critically assessed. A perspective on the future directions for large-scale application of the phenol oxidases in immobilised forms is provided.


2016 ◽  
Vol 59 (2) ◽  
pp. 111-116
Author(s):  
Saadat Ullah ◽  
Ijaz Malook ◽  
Khair Ul Bashar ◽  
Mehvish Riaz ◽  
Muhammad Mudasar Aslam ◽  
...  

Lipases are important hydrolytic enzymes that hydrolyze long chain triacylglycerol intodiacylglycerol, monoacylglycerol, glycerol and fatty acids. Lipases are found in microorganisms, fungi,plants and animals. Commercially, useful extracellular lipases are isolated from different bacterial species,including Bacillus, Achromobacter, Alcaligenes, Arthrobacter, Pseudomonas, Staphylococcus andChromobacterium species. Among the Pseudomonas species, Pseudomonas aeruginosa, P. cepacia andP. fluorescence are the major producers of lipases. Bacterial lipases have great industrial applicationsbecause of their stability, selectivity and broad substrate specificity. Due to their large scale applicationin industrial sectors, attention is given to isolate Pseudomonas lipases. In this review, purification strategiesfor lipases isolated from Pseudomonas species have been focussed.


1969 ◽  
Vol 22 (03) ◽  
pp. 577-583 ◽  
Author(s):  
M.M.P Paulssen ◽  
A.C.M.G.B Wouterlood ◽  
H.L.M.A Scheffers

SummaryFactor VIII can be isolated from plasma proteins, including fibrinogen by chromatography on agarose. The best results were obtained with Sepharose 6B. Large scale preparation is also possible when cryoprecipitate is separated by chromatography. In most fractions containing factor VIII a turbidity is observed which may be due to the presence of chylomicrons.The purified factor VIII was active in vivo as well as in vitro.


1992 ◽  
Vol 70 (6) ◽  
pp. 448-454 ◽  
Author(s):  
Ewa Świeżewska ◽  
T. Chojnacki ◽  
W. J. Jankowski ◽  
K. Singh ◽  
J. Olsson

The long chain polyprenols composed of 30 and more isoprene units from leaves of plants belonging to the genera Potentilla and Rosa have been described. They occur in the form of fatty acid esters. The composition of polyprenol mixture was species dependent and its content reached ca. 0.5% wet weight. Large scale preparation of individual polyprenols from a natural polyprenol mixture was performed using time-extended liquid chromatography on the hydrophobic gel Lipidex-5000.Key words: long chain polyprenols, Rosaceae.


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