Table of Contents
- 1 Does calcium activate isocitrate dehydrogenase?
- 2 How does calcium affect the Krebs cycle?
- 3 What does isocitrate dehydrogenase do in the citric acid cycle?
- 4 Which of the following enzymes of the citric acid cycle is activated by Ca2+?
- 5 How does the pyruvate dehydrogenase reaction control the citric acid cycle?
- 6 Why does NADH inhibit isocitrate dehydrogenase?
- 7 What does Alpha-ketoglutarate dehydrogenase do?
- 8 Is isocitrate to alpha-ketoglutarate reversible?
Does calcium activate isocitrate dehydrogenase?
Calcium ions activate mammalian NAD-isocitrate dehydrogenase by causing a marked decrease in the Km for the substrate threo-ds-isocitrate [3], [70], [71]. The presence of either ADP or ATP is an absolute requirement for calcium sensitivity.
How does calcium affect the Krebs cycle?
Calcium also plays an important role in the regulation of the citric acid cycle by activating pyruvate dehydrogenase, NAD+-dependent isocitrate dehydrogenase, and 2-oxoglutarate dehydrogenase [1], [2], [3], [4], [5], thus allowing the same signal that stimulates muscle contraction to activate the production of ATP to …
What stimulates the enzyme isocitrate dehydrogenase?
The reaction is stimulated by the simple mechanisms of substrate availability (isocitrate, NAD+ or NADP+, Mg2+ / Mn2+ ), product inhibition by NADH (or NADPH outside the citric acid cycle) and alpha-ketoglutarate, and competitive feedback inhibition by ATP.
What does isocitrate dehydrogenase do in the citric acid cycle?
Isocitrate dehydrogenase is a digestive enzyme that is used in the citric acid cycle. Its main function is to catalyze the oxidative decarboxylation of isocitrate into alpha-ketoglutarate.
Which of the following enzymes of the citric acid cycle is activated by Ca2+?
dehydrogenase, isocitrate dehydrogenase, and a-ketoglutarate dehydrogenase, are strongly activated by increases in Ca2+ in that range (4, 5).
Does calcium inhibit PDH?
Pyruvate dehydrogenase complex is inhibited in calcium-loaded cerebrocortical mitochondria. Neurochem Res.
How does the pyruvate dehydrogenase reaction control the citric acid cycle?
Pyruvate dehydrogenase (PDH) is a convergence point in the regulation of the metabolic finetuning between glucose and FA oxidation. Hence, PDH converts pyruvate to acetyl-coA, and thereby increases the influx of acetyl-coA from glycolysis into the TCA cycle.
Why does NADH inhibit isocitrate dehydrogenase?
Human NAD-dependent isocitrate dehydrogenase (NAD-IDH) catalyzes the oxidative decarboxylation of isocitrate in the citric acid cycle. The NADH at the active site occupies the binding site for NAD+ and prevents the binding of the cofactor.
Why is isocitrate dehydrogenase important?
Isocitrate Dehydrogenase. Isocitrate dehydrogenase (IDH) is an important enzyme in the tricarboxylic acid cycle, which occurs in the mitochondrial matrix. IDH is responsible for catalyzing the reversible conversion of isocitrate to alpha-ketoglutarate and CO2 in a two-step reaction (14).
What does Alpha-ketoglutarate dehydrogenase do?
Alpha-ketoglutarate dehydrogenase (α-KGDH) is a highly regulated enzyme, which could determine the metabolic flux through the Krebs cycle. It catalyses the conversion of α-ketoglutarate to succinyl-CoA and produces NADH directly providing electrons for the respiratory chain.
Is isocitrate to alpha-ketoglutarate reversible?
How does NADH regulate the citric acid cycle?
It regulates the speed at which the citrate isomer isocitrate loses a carbon to form the five-carbon molecule α-ketoglutarate. The coenzyme NADH is a product of the reaction and, at high levels, acts as an inhibitor by directly displacing the NAD+ molecules it is formed from.