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[Lateral diffusion of the protein components of the respiratory assembly of Microsoccus lysodeikticus]
Abstract:
Preparations with a selectively decreased (by 85-90%) content of NADH dehydrogenase were isolated by means of heating treatment of M. lysodeikticus isolated membranes. The degree of the reduction of the NADH dehydrogenase nearest neighbour in the respiration chain of cytochrome b556 in heated membranes is similar to that in intact membranes. It is concluded that cytochrome b556 and (or) NADH dehydrogenase are capable to lateral migration in the membrane of M. lysodeikticus, resulting in the inter-chain electrone transport. A coefficient of their lateral diffusion is calculated (D equals 8-10(-10)-2-10(-9) CM2SEC-1 At 30 degrees C) on the basis of kinetics of cytochrome reduction by NADH dehydrogenase. The electron transport, due to a diffusion of respiration carriers from one assambly to another, proceeds 100 times as slow as the electrone transport in the respiratory chain. The data obtained allow to consider the aggregation of respiration enzymes as a dynamic formation.
Insights
NADH dehydrogenase and cytochrome b556 in Micrococcus lysodeikticus membranes exhibit lateral diffusion, enabling inter-chain electron transport. This dynamic enzyme aggregation suggests a flexible respiratory chain mechanism.
Area of Science:
- Biochemistry
- Cell Biology
- Microbiology
Context:
- Investigating the structure and function of respiratory chains in bacterial membranes.
- Understanding the mobility of membrane-bound enzymes and their role in electron transport.
- Utilizing heat treatment to selectively modify enzyme content in isolated membranes.
Purpose:
- To determine if NADH dehydrogenase and cytochrome b556 can migrate within the M. lysodeikticus membrane.
- To investigate the implications of this migration for inter-chain electron transport.
- To quantify the lateral diffusion coefficient of these respiratory components.
Summary:
- Preparations with reduced NADH dehydrogenase (85-90%) were obtained from heated M. lysodeikticus membranes.
- Cytochrome b556 reduction levels were similar in heated and intact membranes, indicating potential lateral migration of cytochrome b556 and/or NADH dehydrogenase.
- The calculated lateral diffusion coefficient (D = 8-10(-10)-2-10(-9) cm²/sec at 30°C) suggests dynamic enzyme aggregation and inter-chain electron transport.
Impact:
- Provides evidence for lateral mobility of respiratory enzymes within bacterial membranes.
- Suggests that enzyme aggregation in respiratory chains is a dynamic process, not a static assembly.
- Offers insights into the mechanisms of electron transport and energy production in bacteria.