Inhibitory effects of 4-halobenzoic acids on the diphenolase and monophenolase activity of mushroom tyrosinase.
The effects of 4-halobenzoic acids (4-fluorobenzoic acid, 4-chlorobenzoic acid, and 4-bromobenzoic acid) on the activity of mushroom tyrosinase have been studied. The results show that 4-halobenzoic acids can strongly inhibit both monophenolase activity and diphenolase activity of the enzyme, and the inhibition displays a reversible course. The IC50 values were estimated as 0.26, 0.20, and 0.18 mM for diphenolase activity and as 1.03, 0.75, and 0.60 mM for monophenolase activity, respectively. Kinetic analyses show that the inhibition mechanism of all three 4-halobenzoic acids is noncompetitive inhibition to the diphenolase activity, and the inhibition constants (K1) were determined to be 0.25, 0.20, and 0.17 mM, respectively. The lag time of the monophenolase was obviously lengthened by these three 4-halobenzoic acids. When the concentration of inhibitors reached 1.4 mM, the lag time was lengthened from 30 s to 120, 125, and 150 s, respectively.
The Key Laboratory of Ministry of Education for Cell Biology and Tumor Cell Engineering, School of Life Sciences, Xiamen University, Xiamen 361005, China.
Qin
Q
Wang
Yan
Y
Shi
Kang-Kang
KK
Song
Hua-Yun
HY
Guo
Ling
L
Qiu
Qing-Xi
QX
Chen
D000363:Agaricales / Q000201:enzymology*; D001565:Benzoates / Q000737:chemistry*; D004295:Dihydroxyphenylalanine / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000737:chemistry*; D006219:Halogens / Q000737:chemistry*; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D010088:Oxidoreductases / Q000737:chemistry
D001565:Benzoates; D004791:Enzyme Inhibitors; D006219:Halogens; D004295:Dihydroxyphenylalanine; D010088:Oxidoreductases; C412191:monophenolase; D014442:Monophenol Monooxygenase