Matheis G, Belitz H D
Z Lebensm Unters Forsch. 1977 Mar 21;163(3):191-5. doi: 10.1007/BF01459856.
From initial velocity studies a sequential mechanism for the reactions catalysed by phenoloxidase from potatoes is indicated. The data are in accordance with an ordered addition of oxygen and phenolic substrate to the enzyme, with oxygen being the first substrate bound at thermodynamic equilibrium. The Michaelis constants for L-tyrosine, L-dopa, and chlorogenic acid are 1.4 X 10(-3), 3.3 X 10(-4), and 1.4 X 10(-4) mol/l, respectively. The dissociation constant for the enzyme-oxygen complex is about 10(-3) mol/l. In the presence of chlorogenic acid no lag phase occurs in the course of L-tyrosine oxidation. With increasing amounts of chlorogenic acid the tyrosinase activity goes through a maximum. The significance of these findings for the in vivo action of the enzyme is discussed.
通过初始速度研究表明了马铃薯酚氧化酶催化反应的顺序机制。数据符合氧气和酚类底物向酶的有序添加，在热力学平衡时氧气是第一个结合的底物。L-酪氨酸、L-多巴和绿原酸的米氏常数分别为1.4×10⁻³、3.3×10⁻⁴和1.4×10⁻⁴mol/L。酶-氧复合物的解离常数约为10⁻³mol/L。在绿原酸存在下，L-酪氨酸氧化过程中没有延迟期。随着绿原酸量的增加，酪氨酸酶活性达到最大值。讨论了这些发现对该酶体内作用的意义。
