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pH ‐induced structural changes of tyrosinase from Agaricus bisporus using fluorescence and in silico methods
Author(s) -
Ioniţă Elena,
Stănciuc Nicoleta,
Aprodu Iuliana,
Râpeanu Gabriela,
Bahrim Gabriela
Publication year - 2014
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.6574
Subject(s) - agaricus bisporus , trimer , chemistry , tetramer , tyrosinase , dimer , browning , enzyme , molecular dynamics , fluorescence , agaricus , protein tertiary structure , stereochemistry , biochemistry , organic chemistry , mushroom , food science , computational chemistry , physics , quantum mechanics
BACKGROUND Tyrosinases are involved in enzymatic browning reactions in damaged fruits during post‐harvest handling and processing. The overall structure of tyrosinase from Agaricus bisporus mushrooms at different pH values was monitored using fluorescence spectroscopy and molecular dynamics simulations.RESULTS When the pH value was increased from 6.0 to 9.0, the protein passed through several structural intermediates, including the tetramer, trimer and dimer stages. Changes in the secondary and tertiary structure of tyrosinase at neutral pH were outlined after running molecular dynamics simulations. A detailed check at the single‐molecule level by means of molecular modeling tools suggested that the most important contribution to the fluorescence intensity is given by the H subunits with seven Trp and nine Tyr residues exposed to the solvent, whereas the lectin‐like folded L subunits have only six Trp and three Tyr residues, of which only Trp 15 , Trp 59 and Trp 93 are partially exposed to the solvent.CONCLUSIONS The results indicated that the enzyme was sensitive to pH . The experimental results revealed the unfolding of the native tetrameric enzyme in acidic pH range, causing exposure of the hydrophobic residues. © 2014 Society of Chemical Industry