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PMID:24613318
| Citation |
Zekiri, F, Molitor, C, Mauracher, SG, Michael, C, Mayer, RL, Gerner, C and Rompel, A (2014) Purification and characterization of tyrosinase from walnut leaves (Juglans regia). Phytochemistry 101:5-15 |
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| Abstract |
Polyphenol oxidase (PPO) is a type-3 copper enzyme catalyzing the oxidation of phenolic compounds to their quinone derivates, which are further converted to melanin, a ubiquitous pigment in living organisms. In this study a plant originated tyrosinase was isolated from walnut leaves (Juglans regia) and biochemically characterized. It was possible to isolate and purify the enzyme by means of an aqueous two-phase extraction method followed by chromatographic purification and identification. Interestingly, the enzyme showed a rather high monophenolase activity considering that the main part of plant PPOs with some exceptions solely possess diphenolase activity. The average molecular mass of 39,047Da (Asp(101)→Arg(445)) was determined very accurately by high resolution mass spectrometry. This proteolytically activated tyrosinase species was identified as a polyphenol oxidase corresponding to the known jrPPO1 sequence by peptide sequencing applying nanoUHPLC-ESI-MS/MS. The polypeptide backbone with sequence coverage of 96% was determined to start from Asp(101) and not to exceed Arg(445). |
| Links |
PubMed Online version:10.1016/j.phytochem.2014.02.010 |
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Significance
Annotations
| Gene product | Qualifier | GO Term | Evidence Code | with/from | Aspect | Extension | Notes | Status |
|---|---|---|---|---|---|---|---|---|
|
enables |
GO:0036263: L-DOPA monooxygenase activity |
ECO:0000314: direct assay evidence used in manual assertion |
F |
Seeded From UniProt |
complete | |||
|
enables |
GO:0004503: monophenol monooxygenase activity |
ECO:0000314: direct assay evidence used in manual assertion |
F |
Seeded From UniProt |
complete | |||
| GO:0004503: monophenol monooxygenase activity |
ECO:0000314: |
F |
Table 3 shows a monophenolase activity of kcat 20.8 s^-1 towards L-tyrosine |
complete | ||||
| GO:0036263: L-DOPA monooxygenase activity |
ECO:0000314: |
F |
Table 3 shows a diphenolase activity of kcat 199.3 s^-1 towards L-dopa |
complete | ||||
See also
References
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