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Purification and characterization of a ketimine-reducing enzyme
M Nardini1, G Ricci, A M Caccuri
1Department of Biochemical Sciences, University of Rome, La Sapeinza, Italy.
European Journal of Biochemistry
|May 2, 1988
Summary
Researchers discovered a pig kidney enzyme that reduces ketimines, a new class of compounds. This reductase may play a role in the biosynthesis of sulfur-containing compounds found in mammals.
Area of Science:
- Biochemistry
- Enzymology
- Metabolic pathways
Background:
- Ketimines are a novel class of cyclic unsaturated compounds.
- These compounds can be formed from the deamination of sulfur-containing amino acids.
- A widespread mammalian transaminase catalyzes ketimine formation.
Purpose of the Study:
- To detect and purify an enzyme capable of reducing ketimines.
- To characterize the molecular and kinetic properties of this reductase.
- To investigate the potential role of this enzyme in mammalian biosynthesis.
Main Methods:
- Enzyme purification (2500-fold) from pig kidney.
- Determination of enzyme kinetics and molecular properties.
- Identification of enzymatic reduction products.
Main Results:
- A novel NAD(P)H-dependent reductase was purified.
- The enzyme follows a ping-pong mechanism, with ketimines as the likely substrate.
- Identified reduction products include cyclothionine and thiomorpholine derivatives.
Conclusions:
- The purified reductase is involved in ketimine metabolism.
- The identified products are found in mammals, suggesting a biosynthetic role for the enzyme.
- This enzyme may contribute to the metabolic pathways of sulfur-containing amino acids.