Successful resonance Raman study of cresolase activity of mushroom tyrosinase.
Mono-oxygenase (cresolase) activity of mushroom tyrosinase (MT) in the presence of 4-[(4-hydroxyphenyl)azo]-benzenesulfonamide (HPABS) was successfully studied by resonance Raman (rR) spectroscopy. HPABS is a synthetic competitive inhibitor (K(i)=7.17 x 10(-6)M) for the cresolase activity with a large extinction coefficient at 365 nm. Upon reacting with MT, HPABS produced an enzyme-inhibitor (EI) complex with sufficiently long life span. Analyzing the ensuing spectrum indicates that the azo tautomer of HPABS binds to the enzyme and retains its geometrical isomeric form in the EI complex. The observed changes in the rR spectrum of HPABS after binding to MT support the idea that an electrophilic attack on the inhibitor has happened. Similar experiments were designed for studying the oxidase activity of MT. However, the enzymatic reaction, even in the presence of 4-[(2,4-dinitrophenyl)azo]-1,2-benzenediols was still fast enough to tan the reaction solution quickly and render its rR spectrum impregnable background.
Shareefi Borojerdi
S
S
Biochemistry Department, National Research Center for Genetic Engineering and Biotechnology, Tehran, Iran.
Haghbeen
Kamahldin
K
Asghar Karkhane
Ali
A
Fazli
Mustafa
M
Saboury
Ali Akbar
AA
D000363:Agaricales / Q000201:enzymology*; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman / Q000379:methods*
D014442:Monophenol Monooxygenase