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Urate-oxidase in liver of oxonic acid treated mice
Abstract:
Following a single intraperitoneal injection of oxonic acid, urate-oxidase inhibitor with optical and chromatographic properties of the injected drug was found in the supernatants of mouse liver homogenates. Maximal inhibitory activity of 40 000 g-20 minutes supernatants against Sigma urate-oxidase was found 30 minutes after injection, and it almost disappeared after six hours. In whole homogenates, urate-oxidase activity was found 50% inhibited at 30 minutes, and it returned to normal levels between 3 and 6 hours following injection. Urate-oxidase activity of resuspended nuclei-free 40 000 g particles from these homogenates showed a significative increase of activity over controls during the first three hours after injection, and it returned to a normal level between 3 and 6 hours after injection. There was, instead, no increase of activity in 40 000 g-20 minutes particles suspensions when these were separated from homogenates prepared from untreated mice and incubated with oxonic acid.
Insights
Oxonic acid, a urate-oxidase inhibitor, was injected into mice. Its inhibitory activity peaked at 30 minutes, with liver urate-oxidase returning to normal levels within 3-6 hours post-injection.
Area of Science:
- Biochemistry
- Pharmacology
- Enzymology
Background:
- Urate-oxidase is a key enzyme in purine metabolism.
- Oxonic acid is a known inhibitor of urate-oxidase.
- Understanding enzyme inhibition kinetics is crucial for drug development.
Purpose of the Study:
- To investigate the time-dependent effects of oxonic acid on mouse liver urate-oxidase activity.
- To characterize the distribution and activity of oxonic acid in mouse liver homogenates.
Main Methods:
- Intraperitoneal injection of oxonic acid in mice.
- Preparation of mouse liver homogenates and subcellular fractions (40,000g supernatants and particles).
- Assay of urate-oxidase activity and inhibitory effects of oxonic acid using Sigma urate-oxidase as a standard.
Main Results:
- Oxonic acid was detected in liver homogenate supernatants post-injection.
- Maximal urate-oxidase inhibition occurred at 30 minutes, diminishing by 6 hours.
- Nuclei-free particles showed increased urate-oxidase activity within 3 hours, returning to normal by 6 hours.
Conclusions:
- Oxonic acid exhibits transient inhibitory effects on mouse liver urate-oxidase.
- Subcellular localization influences the observed changes in enzyme activity post-inhibition.
- The study provides insights into the pharmacokinetics and pharmacodynamics of oxonic acid in vivo.