Formaldehyde dehydrogenase from Pseudomonas putida. Purification and some properties.

Area of Science:

• Biochemistry
• Enzymology
• Microbial Metabolism

Background:

• Formaldehyde dehydrogenase (FDH) plays a crucial role in formaldehyde metabolism.
• Understanding FDH from diverse microbial sources is important for biotechnological applications.
• Pseudomonas putida C-83 is a bacterium known to metabolize various organic compounds.

Purpose of the Study:

• To isolate and purify formaldehyde dehydrogenase from Pseudomonas putida C-83.
• To characterize the biochemical and kinetic properties of the purified enzyme.
• To compare the enzyme with FDHs from other sources.

Main Methods:

• Enzyme purification using sequential column chromatographies (DEAE-cellulose, DEAE-Sephadex A-50, hydroxyapatite).
• Enzyme homogeneity assessed by disc gel electrophoresis.
• Enzyme activity assays at various pH and substrate concentrations.
• Determination of molecular weight (gel filtration) and subunit composition (SDS-PAGE).
• Kinetic analysis (Km values, reaction mechanism).

Main Results:

• Purified homogeneous formaldehyde dehydrogenase with 12% yield.
• Optimal activity at pH 7.8, utilizing formaldehyde as substrate.
• NAD+-dependent enzyme, not requiring glutathione.
• Inhibition by heavy metal ions (Ni2+, Pd2+, Hg2+) and specific inhibitors.
• Estimated molecular weight of 150,000 Da, composed of two subunits.
• Km values: 67 µM for formaldehyde, 56 µM for NAD+.
• Reaction proceeds via a 'Ping-pong' mechanism.

Conclusions:

• Successfully purified and characterized a novel formaldehyde dehydrogenase from Pseudomonas putida C-83.
• The enzyme exhibits unique properties compared to FDHs from other organisms, particularly its cofactor dependency and lack of glutathione requirement.
• The kinetic properties suggest potential for specific biotechnological applications in formaldehyde oxidation.