Characterization of the activity of tyrosinase on betaxanthins derived from (R)-amino acids |
| |
Authors: | Gandía-Herrero Fernando Escribano Josefa García-Carmona Francisco |
| |
Affiliation: | Departamento de Bioquímica y Biología Molecular A, Facultad de Veterinaria, Universidad de Murcia, E-30100 Espinardo, Murcia, Spain. |
| |
Abstract: | The activity of tyrosinase (EC 1.14.18.1) on selected (R)-betaxanthins is characterized in depth, demonstrating that the activity of the enzyme is not restricted to betaxanthins derived from (S)-amino acids. Conversion of (R)-tyrosine-betaxanthin [(R)-portulacaxanthin II] to the pigment (R)-dopaxanthin and its further oxidation to a series of products is described. Compound identity was studied by high performance liquid chromatography and electrospray ionization-mass spectrometry. The reaction rate on the (R)-isomer of dopaxanthin is 1.9-fold lower than that obtained for the (S)-isomer in previous studies. Tyrosinase showed stereospecificity in its affinity toward betaxanthins. The characterization of the activity of tyrosinase on (R)-betaxanthins reinforces the role of the enzyme in the biosynthetic scheme of betalains. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|