Cytochemical model system for microsomal rat liver glucose-6-phosphate

Area of Science:

• Biochemistry
• Enzymology
• Histochemistry

Background:

• Glucose-6-phosphatase is a key enzyme in glucose metabolism, primarily located in the liver microsomes.
• Accurate measurement of enzyme activity is crucial for understanding metabolic disorders.
• Previous methods for incorporating enzymes into polyacrylamide films resulted in significant activity loss.

Purpose of the Study:

• To develop a method for incorporating rat liver microsomal glucose-6-phosphatase into polyacrylamide films while preserving enzymatic activity.
• To compare the biochemical and histochemical properties of the incorporated enzyme with its behavior in suspension.
• To establish a protocol for electron-microscopical investigation of enzyme-embedded films.

Main Methods:

• Incorporation of rat liver microsomal fraction into polyacrylamide films using a modified polymerization method.
• Biochemical assays to determine glucose-6-phosphatase activity and inhibition patterns (alloxan, HgCl2, pH 5.0 acetate buffer).
• Histochemical analysis using the Wachstein and Meisel lead method.
• Electron microscopy preparation using Epon embedding with dimethyl sulfoxide dehydration.

Main Results:

• The modified method retained approximately 90% of glucose-6-phosphatase activity in polyacrylamide films.
• The incorporated enzyme exhibited inhibition patterns similar to the enzyme in suspension.
• Biochemical and histochemical analyses showed good correlation after glutaraldehyde fixation.
• A reliable method for Epon embedding of films for electron microscopy was established.

Conclusions:

• The developed method effectively preserves glucose-6-phosphatase activity in polyacrylamide films.
• This technique allows for reliable biochemical and histochemical assessment of enzyme function.
• The method is suitable for electron-microscopical studies, offering insights into enzyme localization and structure.