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2,3,4‐TRIHYDROXYACETOPHENONE (2,3,4‐THAP) AS A SUBSTRATE FOR MUSHROOM TYROSINASE 1
Author(s) -
KAHN VARDA
Publication year - 1990
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.1990.tb00833.x
Subject(s) - quinone , substrate (aquarium) , chemistry , tetramer , dimer , product (mathematics) , stereochemistry , biochemistry , organic chemistry , biology , enzyme , mathematics , ecology , geometry
2,3,4‐Trihydroxyacetophenone (2,3,4‐THAP) can serve as a substrate for mushroom tyrosinase with a K m value of 1.2 mM. The product(s) formed is yellow, characterized by a peak at 420–430 nm . A lag period in 2,3,4‐THAP oxidation to the yellow product(s) in the presence of ascorbate indicates that the initial product(s) is an o‐quinone of 2,3,4‐THAP. An oxime, characterized by a broad peak at 510–650 nm, is the likely product formed between o‐quinone of 2,3,4‐THAP and NH 2 OH. The ɛ m of the o‐quinone of 2,3,4‐THAP was estimated to be 1.6 × 10 4 M −1 cm −1 at 425 nm. During relatively long incubation periods, the peak of the yellow product(s) shifts from 420–425 nm to 430–440 nm; the solution remains yellow and transparent for at least a week and no precipitate is formed. The final yellow product(s) is probably a low molecular weight polymer of THAP‐o‐quinone (dimer, tetramer, etc).