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Gouzi H.,UPMC P6 | Coradin T.,UPMC P6 | Delicado E.N.,University of Murcia | Umit Unal M.,Cukurova University | Benmansour A.,Abou Bekr Belkaid University Tlemcen
Open Enzyme Inhibition Journal | Year: 2010

This paper reports the inhibition kinetics of mushroom (Agaricus bisporus; J.E. Lange) polyphenol oxidase (PPO) with benzoic acid, sodium azide and sodium fluoride as inhibitors, and pyrocatechol as substrate. Mushroom PPO was significantly inhibited by all of the tested inhibitors. Diphenolase activity of mushroom PPO exhibited the competitive-type inhibition with benzoic acid as an inhibitor; the inhibition constant KI was found to be 0.046 mM. The inhibition by sodium azide was of the mixed-I type, with a KI of 1.39 mM and KIS of 3.12 mM. A partial mixed-type inhibition pattern was obtained with sodium fluoride, with a KI of 148.97 mM and a KIS of 49.19 mM. The IC50 values were estimated to be 0.147, 3.20, and 123.94 mM for benzoic acid, sodium azide, and sodium fluoride, respectively. Furthermore, benzoic acid was the most effective inhibitor because of its low KI value. The results showed that the type of inhibition was dependent upon both the origin of the PPO and on the substrate. © Gouzi et al.

Bouyarmane H.,Mohammed V University | Asri S.E.,Mohammed V University | Rami A.,Laboratoire National Of Controle Des Medicaments | Roux C.,UPMC P6 | And 4 more authors.
Journal of Hazardous Materials | Year: 2010

A natural phosphate rock and two synthetic mesoporous hydroxyapatites were evaluated for the removal of pyridine and phenol from aqueous solutions. Experiments performed by the batch method showed that the sorption process occurs by a first order reaction for both pyridine and phenol. In contrast, the Freundlich model was able to describe sorption isotherms for phenol but not for pyridine. In parallel, the three apatites exhibit similar pyridine sorption capacities whereas phenol loading was in agreement with their respective specific surface area. This was attributed to the strong interaction arising between pyridine and apatite surface that hinders further inter-particular diffusion. This study suggests that, despite its low specific surface area, natural phosphate rock may be used as an efficient sorbent material for specific organic pollutants, with comparable efficiency and lower processing costs than some activated carbons. © 2010 Elsevier B.V.

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