Reversible sodium dodecyl sulfate activation of latent peach polyphenol oxidase by cyclodextrins

The reversibility of the SDS-mediated activation of latent peach PPO has be en studied using cyclodextrins as strip detergent agent. Cyclodextrins prod uced a combined inhibitory effect on enzymatic activity of latent peach PPO due to the complexation of detergent and the hydrophobic substrate 4-tert- butylcatechol (TBC) molecules. To study the reversibility of the activation process, this combined effect has to be separated. On the one hand, the en zyme was activated by acid-shocking and the activity was measured in the pr esence of cyclodextrins, using TBC as substrate. The inhibition curves obta ined permitted study of the complexation of TBC into cyclodextrins. On the other hand, the enzyme was activated by SDS and the activity in the presenc e of cyclodextrins was measured using the highly hydrophilic o-diphenol dop amine as substrate. In this case, the inhibition curves obtained indicated the reversibility of the activation process when SDS was trapped by cyclode xtrins, In addition, the complexation constant between SDS and 2-hydroxypro pyl-beta-cyclodextrins was calculated by measuring conductivity (K-s = 3500 M-1). (C) 2000 Academic Press.