The calcium-dependent enzyme activity which hydrolyzes the p-nitrophenyl-O-P bond of paraoxon (paraoxonase) has been studied in several rat and human tissues. Rat plasma and liver showed the highest activities (1.31 +/- 0.19, 0.82 +/- 0.09 nmol/min mg protein +/- SEM, respectively), while other tissues showed less than 2% plasma activity. The Arrhenius plot showed monophasic patterns in both tissues with activation energy values of Ea = 57 +/- 3 and 69 +/- 4 kcal/mol degree K for rat liver and plasma, respectively. Rat plasma and liver paraoxonase lost about 80% activity after 24-hr storage at 27-30 degrees C and was not restored by calcium addition. There was no loss of activity in human serum after 3 days and only 33% after 5 days. The pH optimum for paraoxonase activities was about 7.4 for both rat tissues. It is concluded that plasma paraoxonase is similar to the liver enzyme and is a good mirror for total body detoxifying activity.
|Titolo:||Distribution and some biochemical properties of rat paraoxonase activity|
MORETTO, ANGELO (Secondo)
|Parole Chiave:||A-esterase; Detoxification; Organophosphorus; Paraoxon; Paraoxonase; Rat|
|Settore Scientifico Disciplinare:||Settore MED/44 - Medicina del Lavoro|
|Data di pubblicazione:||1990|
|Digital Object Identifier (DOI):||10.1016/0892-0362(90)90071-J|
|Appare nelle tipologie:||01 - Articolo su periodico|