The action of a binary nonionic detergent on a kidney membrane fraction

Area of Science:

• Biochemistry
• Membrane Biology
• Cellular Physiology

Background:

• Kidney cortex microsomal membranes contain vital transport proteins like (Na+, K+)-ATPase.
• Detergent-mediated membrane disruption is crucial for isolating membrane proteins for study.

Purpose of the Study:

• To investigate the mechanism of kidney cortex microsomal membrane disruption by a binary, nonionic detergent.
• To quantify the effect of detergent treatment on (Na+, K+)-ATPase activity and protein release.

Main Methods:

• Monitoring total protein and (Na+, K+)-ATPase activity in supernatant fractions after detergent treatment.
• Analyzing changes in critical micelle concentration (cmc) under varying detergent and protein concentrations.
• Utilizing Hill plots to assess detergent-membrane interactions and binding stoichiometry.

Main Results:

• Both total protein and (Na+, K+)-ATPase markers responded similarly to pH, microsome, and detergent concentrations.
• (Na+, K+)-ATPase activity increased significantly (2.2-fold single, 3.5-fold sequential treatment).
• Detergent monomers interact with membranes, and micelles facilitate enzyme release above the cmc.

Conclusions:

• Membrane disruption involves initial detergent monomer binding followed by co-micelle formation.
• This process enhances the release and activity of membrane-bound enzymes like (Na+, K+)-ATPase.
• Understanding these interactions is key for effective membrane protein isolation and biochemical analysis.