Glucose dehydrogenase in teleosts: tissue distribution and proposed function

Area of Science:

• Biochemistry
• Marine Biology
• Enzymology

Background:

• Glucose dehydrogenase (EC 1.1.1.47) is an enzyme involved in glucose metabolism.
• The mixed-function oxidase system is crucial for detoxification and metabolic processes in fish.
• Understanding enzyme distribution and function is key to comprehending fish physiology.

Purpose of the Study:

• To investigate the presence and distribution of glucose dehydrogenase activity in various marine teleost fish tissues.
• To explore interordinal variations in glucose dehydrogenase enzymatic activity.
• To evaluate the potential role of glucose dehydrogenase in providing NADPH for the mixed-function oxidase system.

Main Methods:

• Electrophoretic examination of tissue extracts from skeletal muscle, heart, eye, brain, liver, kidney, gill, and stomach.
• Analysis of 21 species of marine teleost fishes.
• Quantification of glucose dehydrogenase activity.

Main Results:

• Glucose dehydrogenase activity was exclusively detected in liver extracts across all examined species.
• Significant interordinal variation in the levels of glucose dehydrogenase enzymatic activity was observed.
• The study identified specific marine teleost species with high glucose dehydrogenase activity in their livers.

Conclusions:

• Glucose dehydrogenase is primarily expressed in the liver of marine teleost fishes.
• Enzymatic activity levels exhibit substantial variation among different fish orders.
• The findings support the hypothesis that glucose dehydrogenase serves as a source of NADPH for the mixed-function oxidase system in teleosts.