Flavin-linked mitochondrial alpha-glycerophosphate dehydrogenase of Candida utilis

Area of Science:

• Biochemistry
• Enzymology
• Microbial Physiology

Background:

• L-alpha-glycerophosphate dehydrogenase is a key enzyme in cellular respiration.
• Understanding its properties in different yeast species is crucial for metabolic studies.
• Electron-transport particles contain essential enzymes for energy production.

Purpose of the Study:

• To purify and characterize L-alpha-glycerophosphate dehydrogenase from Candida utilis electron-transport particles.
• To investigate the enzyme's cofactor and metal content.
• To compare its presence and activity in Candida utilis and Saccharomyces cerevisiae.

Main Methods:

• Mild purification procedures for enzyme isolation.
• Enzyme activity assays.
• Spectroscopic analysis for cofactor and metal identification.
• Molecular weight determination.
• Growth condition studies in yeast.

Main Results:

• Achieved 150-fold purification of the enzyme using mild methods.
• The purified enzyme contains flavin adenine dinucleotide (FAD), iron, and copper.
• The enzyme has a molecular weight of approximately 5 x 10(5) Da and a complex subunit composition.
• Enzyme activity is low in Saccharomyces cerevisiae, particularly when grown on glucose, but present when grown on glycerol.
• NAD-dependent cytoplasmic alpha-glycerophosphate dehydrogenase was found in C. utilis but not in glucose-grown S. cerevisiae.

Conclusions:

• Candida utilis possesses a distinct L-alpha-glycerophosphate dehydrogenase in its electron-transport particles, characterized by FAD, iron, and copper.
• The enzyme's purification was successful despite contamination with proteases, indicating its stability under mild conditions.
• Differential expression and activity of alpha-glycerophosphate dehydrogenase in yeast species are influenced by growth substrates, highlighting metabolic flexibility.