Glutamate dehydrogenase from apodachlya (oomycetes)

Area of Science:

• Biochemistry
• Enzymology
• Mycology

Background:

• Glutamate dehydrogenase (GDH) plays a crucial role in amino acid metabolism.
• Understanding GDH in lower eukaryotes like Apodachlya brachynema can provide insights into metabolic diversity.

Purpose of the Study:

• To purify and characterize the glutamate dehydrogenase from Apodachlya brachynema.
• To investigate the coenzyme and substrate specificity of the purified enzyme.
• To determine the regulatory mechanisms controlling the synthesis of this enzyme.

Main Methods:

• Enzyme purification using standard biochemical techniques.
• Characterization of enzyme kinetics and specificity.
• Analysis of enzyme synthesis regulation under different carbon and nitrogen sources.

Main Results:

• A glutamate dehydrogenase specific for nicotinamide-adenine-dinucleotide (NAD+) was purified 50-fold.
• The enzyme's physical, chemical, and kinetic properties were elucidated.
• Enzyme synthesis was repressed by glucose and induced by amino acids (glutamate, proline, alanine) or ornithine plus aspartate.

Conclusions:

• The data suggest that the primary function of this NAD+-dependent glutamate dehydrogenase in Apodachlya brachynema is degradative.
• No evidence was found for a nicotinamide-adenine-dinucleotide-phosphate (NADP+)-specific biosynthetic glutamate dehydrogenase in this organism.