Reverse Krebs cycle: Difference between revisions
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<StructureSection load='3pff' size='350' side='right' scene='47/477091/Cv/1' caption='ATP-citrate synthase complex with ADP (stick model), tartrate and Mg+2 ions (green), [[3pff]]'> | <StructureSection load='3pff' size='350' side='right' scene='47/477091/Cv/1' caption='ATP-citrate synthase complex with ADP (stick model), tartrate and Mg+2 ions (green), [[3pff]]'> | ||
The reverse Krebs cycle (also known as the reverse tricarboxylic acid cycle, the reverse TCA cycle, or the reverse citric acid cycle, or the reductive tricarboxylic acid cycle, or the reductive TCA cycle) is a sequence of chemical reactions that are used by some bacteria to produce carbon compounds from carbon dioxide and water by the use of energy-rich reducing agents as electron donors. See also [https://en.wikipedia.org/wiki/Reverse_Krebs_cycle] and [[Carbon Fixation]]. | The reverse Krebs cycle (also known as the reverse tricarboxylic acid cycle, the reverse TCA cycle, or the reverse citric acid cycle, or the reductive tricarboxylic acid cycle, or the reductive TCA cycle) is a sequence of chemical reactions that are used by some bacteria to produce carbon compounds from carbon dioxide and water by the use of energy-rich reducing agents as electron donors. See also [https://en.wikipedia.org/wiki/Biological_carbon_fixation], [https://en.wikipedia.org/wiki/Reverse_Krebs_cycle], and [[Carbon Fixation]]. | ||
The cycle involves the biosynthesis of <scene name='43/430893/Cv/2'>Acetyl-CoA</scene> from two molecules of CO2. The key steps of the reverse Krebs cycle are: | The cycle involves the biosynthesis of <scene name='43/430893/Cv/2'>Acetyl-CoA</scene> from two molecules of CO2. The key steps of the reverse Krebs cycle are: | ||
* <scene name='43/430893/Cv/3'>Oxaloacetate</scene> to <scene name='43/430893/Cv/12'>malate</scene>, using NADH + H+ | * <scene name='43/430893/Cv/3'>Oxaloacetate</scene> to <scene name='43/430893/Cv/12'>malate</scene>, using NADH + H+ | ||
*Fumarate to succinate, catalyzed by an oxidoreductase, Fumarate reductase (''e.g.'' [[1d4c]]) | |||
Oxaloacetate + NADH/H+ -> Malate + NAD+ | |||
*<scene name='43/430893/Cv/11'>Fumarate</scene> to <scene name='43/430893/Cv/10'>succinate</scene>, catalyzed by an [[oxidoreductase]], Fumarate reductase (''e.g.'' [[1d4c]]). | |||
Fumarate + FADH2 <=> Succinate + FAD | |||
*Succinate to <scene name='43/430893/Cv/9'>Succinyl-CoA</scene>, an ATP dependent step | |||
Succinate + ATP + CoA -> Succinyl-CoA + ADP + Pi | |||
*<scene name='43/430893/Cv/8'>α-Ketoglutarate</scene> to <scene name='43/430893/Cv/6'>isocitrate</scene>, using NADPH + H+ and another molecule of CO2 | |||
α-Ketoglutarate + CO2 + NAD(P)H/H+ -> Isocitrate + NAD(P)+ | |||
*<scene name='43/430893/Cv/4'>Citrate</scene> converted into <scene name='43/430893/Cv/3'>oxaloacetate</scene> and acetyl-CoA, this is an ATP dependent step and the key enzyme is the [[ATP-citrate synthase|ATP citrate lyase]]. | |||
Citrate + ATP + CoA -> Oxaloacetate + Acetyl-CoA + ADP + Pi | |||
This pathway is cyclic due to the regeneration of the oxaloacetate. | |||
</StructureSection> | </StructureSection> | ||
== References == | == References == | ||
<references/> | <references/> | ||
Latest revision as of 16:56, 5 January 2023
The reverse Krebs cycle (also known as the reverse tricarboxylic acid cycle, the reverse TCA cycle, or the reverse citric acid cycle, or the reductive tricarboxylic acid cycle, or the reductive TCA cycle) is a sequence of chemical reactions that are used by some bacteria to produce carbon compounds from carbon dioxide and water by the use of energy-rich reducing agents as electron donors. See also [1], [2], and Carbon Fixation. The cycle involves the biosynthesis of from two molecules of CO2. The key steps of the reverse Krebs cycle are:
Oxaloacetate + NADH/H+ -> Malate + NAD+
Fumarate + FADH2 <=> Succinate + FAD
Succinate + ATP + CoA -> Succinyl-CoA + ADP + Pi
α-Ketoglutarate + CO2 + NAD(P)H/H+ -> Isocitrate + NAD(P)+
Citrate + ATP + CoA -> Oxaloacetate + Acetyl-CoA + ADP + Pi This pathway is cyclic due to the regeneration of the oxaloacetate.
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