Ros J R, Rodríguez-López J N, García-Cánovas F
Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universidad de Murcia, Spain.
Biochem J. 1993 Oct 1;295 ( Pt 1)(Pt 1):309-12. doi: 10.1042/bj2950309.
The effect of ascorbic acid on the monophenolase activity of tyrosinase, using tyrosine as substrate, has been studied. Over the ranges of ascorbic acid concentration used, no direct effect on the enzyme is found. However, a shortening of the characteristic induction period of the hydroxylation reaction is observed. The evolution of the reaction is dependent on the concentration of ascorbic acid. Low concentrations permit the system to reach the steady state when all ascorbic acid is consumed, whereas high concentrations do not. In the light of these results it is proposed that the influence of ascorbic acid on the reaction is due to its ability to reduce the enzymically generated o-quinones. A relationship between the ascorbic acid concentration, and the induction period generated by it, with the diphenolase activity of tyrosinase is established, which can be used as a basis for the determination of trace amounts of this reducing agent.
以酪氨酸为底物，研究了抗坏血酸对酪氨酸酶单酚酶活性的影响。在所使用的抗坏血酸浓度范围内，未发现对该酶有直接影响。然而，观察到羟基化反应特征诱导期缩短。反应进程取决于抗坏血酸的浓度。低浓度时，当所有抗坏血酸消耗殆尽，体系可达到稳态，而高浓度时则不然。根据这些结果，提出抗坏血酸对反应的影响是由于其还原酶促生成的邻醌的能力。建立了抗坏血酸浓度及其产生的诱导期与酪氨酸酶双酚酶活性之间的关系，可作为测定痕量该还原剂的基础。
