Acetyl-CoA carboxylase is the principal regulation point in the biosynthesis of fatty acids. Some of the properties of the enzyme include: 1. Addition of citrate or isocitrate raises the Vmax of the enzyme as much as 10-fold. 2. The enzyme exists in two interconvertible forms that differ markedly in their activities: Protomer (inactive) filamentous polymer (active) Citrate and isocitrate bind preferentially to the filamentous form, and palmitoyl-CoA binds preferentially to the protomer. Select the true statements that explain how these properties are consistent with the regulatory role of acetyl-CoA carboxylase in the biosynthesis of fatty acids. High citrate and isocitrate levels indicate that there is plenty of ATP, reduced pyridine nucleotides, and acetyl-CoA for fatty acid synthesis. Palmitoyl-CoA is a feedback inhibitor, driving the equilibrium in the direction of the inactive (protomer) form. Palmitoyl-CoA triggers phosphorylation to inactivate the enzyme. Citrate and isocitrate are the precursors for acetyl-CoA synthesis in the mitochondria, thus providing the starting material for fatty acid biosynthesis. ▶ ☐ The protomer and filamentous polymer are the two subunits of acetyl-CoA carboxylase that hold the biotin carrier protein, which rotates between the subunits depending on which compound is bound.
Acetyl-CoA carboxylase is the principal regulation point in the biosynthesis of fatty acids. Some of the properties of the enzyme include: 1. Addition of citrate or isocitrate raises the Vmax of the enzyme as much as 10-fold. 2. The enzyme exists in two interconvertible forms that differ markedly in their activities: Protomer (inactive) filamentous polymer (active) Citrate and isocitrate bind preferentially to the filamentous form, and palmitoyl-CoA binds preferentially to the protomer. Select the true statements that explain how these properties are consistent with the regulatory role of acetyl-CoA carboxylase in the biosynthesis of fatty acids. High citrate and isocitrate levels indicate that there is plenty of ATP, reduced pyridine nucleotides, and acetyl-CoA for fatty acid synthesis. Palmitoyl-CoA is a feedback inhibitor, driving the equilibrium in the direction of the inactive (protomer) form. Palmitoyl-CoA triggers phosphorylation to inactivate the enzyme. Citrate and isocitrate are the precursors for acetyl-CoA synthesis in the mitochondria, thus providing the starting material for fatty acid biosynthesis. ▶ ☐ The protomer and filamentous polymer are the two subunits of acetyl-CoA carboxylase that hold the biotin carrier protein, which rotates between the subunits depending on which compound is bound.
Biochemistry
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Chapter1: Biochemistry: An Evolving Science
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Acetyl-CoA carboxylase is the principal regulation point in the biosynthesis of fatty acids. Some of the properties of the
enzyme include:
1. Addition of citrate or isocitrate raises the Vmax of the enzyme as much as 10-fold.
2. The enzyme exists in two interconvertible forms that differ markedly in their activities:
Protomer (inactive) filamentous polymer (active)
Citrate and isocitrate bind preferentially to the filamentous form, and palmitoyl-CoA binds preferentially to the protomer.
Select the true statements that explain how these properties are consistent with the regulatory role of acetyl-CoA
carboxylase in the biosynthesis of fatty acids.
High citrate and isocitrate levels indicate that there is plenty of ATP, reduced pyridine nucleotides, and acetyl-CoA for
fatty acid synthesis.
Palmitoyl-CoA is a feedback inhibitor, driving the equilibrium in the direction of the inactive (protomer) form.
Palmitoyl-CoA triggers phosphorylation to inactivate the enzyme.
Citrate and isocitrate are the precursors for acetyl-CoA synthesis in the mitochondria, thus providing the starting
material for fatty acid biosynthesis.
The protomer and filamentous polymer are the two subunits of acetyl-CoA carboxylase that hold the biotin carrier
protein, which rotates between the subunits depending on which compound is bound.
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Acetyl-CoA carboxylase (EC 6.4.1.2) is a biotin-dependent enzyme. It is responsible for the carboxylation of acetyl-CoA to form malonyl-CoA. For this, it performs two activities: carboxyl transferase and biotin carboxylase. It performs the first step in fatty acid synthesis.
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