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Two malic enzymes in Pseudomonas aeruginosa
Journal of Bacteriology
|October 1, 1973
Summary
Pseudomonas aeruginosa possesses two distinct malic enzymes, one dependent on nicotinamide adenine dinucleotide (NAD) and the other on NAD phosphate (NADP). These enzymes catalyze reversible reactions crucial for bacterial metabolism.
Area of Science:
- Biochemistry
- Enzymology
- Microbial Metabolism
Background:
- Pseudomonas aeruginosa cell-free extracts lack malic dehydrogenase.
- Previous studies suggested the presence of malic enzyme activity.
Purpose of the Study:
- To confirm and characterize the malic enzyme activity in Pseudomonas aeruginosa.
- To differentiate between NAD-dependent and NADP-dependent malic enzymes.
Main Methods:
- Enzyme assays measuring product formation and stoichiometry.
- Heat stability and partial purification techniques.
- Gel filtration and sucrose density gradient centrifugation for molecular weight determination.
Main Results:
- Two distinct malic enzymes were identified: one NAD-specific and one NADP-specific.
- Both enzymes require bivalent metal cations (Mn2+ > Mg2+).
- The NADP-dependent enzyme is activated by K+ and NH4+; both enzymes are reversible.
Conclusions:
- Pseudomonas aeruginosa possesses distinct NAD- and NADP-dependent malic enzymes.
- These enzymes play a role in the bacterium's metabolic pathways.
- Characterization provides insights into enzymatic mechanisms and cofactor specificity.