Kinetic characterisation and thermal inactivation study of polyphenol oxidase and peroxidase from table grape (Crimson Seedless)
Author/s
Carreño, Juan; López Miranda, Santiago; Serrano Martínez, Ana Agustina; Núñez Delicado, Estrella; Fortea Gorbe, María IsabelDate
2009Discipline/s
Ciencias de la AlimentaciónSubject/s
Polyphenol oxidasePeroxidase Grape
Thermal inactivation SDS
Crimson Seedless
Kinetic parameters
Abstract
Polyphenol oxidase (PPO) and peroxidase (POD) were extracted from a table grape (Crimson Seedless)
using Triton X-114 and characterized using spectrophotometric methods. Both PPO and POD were activated
by acid shock. However, in the presence of the anionic detergent sodium dodecil sulphate (SDS),
PPO was activated whereas POD was inactivated. The enzymes were kinetically characterized and both
followed Michaelis–Menten kinetics, although with different values of their kinetic parameters. The
Vm/Km ratio showed that Crimson Seedless grape PPO presents a similar affinity for 4-tert-butyl-catechol
(TBC) whether activated by acid shock (0.018 min1
) or SDS (0.023 min1
). With regards to POD, the Km
and Vm values for 2,20
-azinobis(3-ethylbenzothiazolinesulphonic acid) (ABTS) were 0.79 mM and
1.20 lM/min, respectively. In the case of H2O2, the Km and Vm value were 0.4 mM and 0.93 lM/min,
respectively. PPO and POD showed similar thermostability, losing >90% of relative activity a...