Related Experiment Videos
[Properties of lactate dehydrogenase of brain mitochondria]
Abstract:
The activity of lactate dehydrogenase in the brain mitochondria isolated within the phycol density gradient accounts for 5% of the enzyme activity determined in cytoplasm. More than 80% of this activity is found in the intermembrane space of mitochondria. Purification, washing and incubation of the mitochondria with supernatant fluid do not change the activity. The treatment with lubrol, desoxycholate or ultrasound evoked almost a two-fold increase in the enzymic activity in the mitochondria and does not change it in the supernatant fluid. Rotenone and Ca2+ have no effect on the activity of lactate dehydrogenase in the both preparations, KCN inhibits it. Mg2+ increases the activity in the supernatant fluid and decreases it in the mitochondria. The relative amount of M- and N- forms of lactate dehydrogenase is approximately the same in the both studied objects.
Insights
Lactate dehydrogenase activity in brain mitochondria is low, primarily located in the intermembrane space. Detergent or ultrasound treatment significantly increases this mitochondrial enzyme activity.
Area of Science:
- Biochemistry
- Cell Biology
- Enzymology
Context:
- Investigating the subcellular localization and regulation of lactate dehydrogenase (LDH) in brain mitochondria.
- Understanding the enzyme's activity within the mitochondrial intermembrane space.
Purpose:
- To quantify lactate dehydrogenase activity in isolated brain mitochondria.
- To determine the effect of various treatments on mitochondrial LDH activity and localization.
- To analyze the influence of specific ions and inhibitors on LDH activity.
Summary:
- Lactate dehydrogenase activity in brain mitochondria represents 5% of cytoplasmic activity, with over 80% localized to the intermembrane space.
- Detergent (lubrol, desoxycholate) or ultrasound treatment doubles mitochondrial LDH activity without affecting cytoplasmic activity.
- Potassium cyanide (KCN) inhibits LDH activity, while magnesium ions (Mg2+) decrease mitochondrial activity and increase cytoplasmic activity. Rotenone and calcium ions (Ca2+) show no effect.
Impact:
- Provides insights into the compartmentalization and regulation of LDH within brain cells.
- Highlights the potential for modulating mitochondrial LDH activity through specific treatments.
- Contributes to the understanding of cellular energy metabolism and enzyme function in the brain.