Adenylate kinase

Adenylate Kinase

Structure of adenylate kinase

Adenylate kinase is an important enzyme in cellular energy metabolism. It catalyzes the interconversion of adenine nucleotides, which is crucial for maintaining the energy balance within the cell. The enzyme is found in various cellular compartments and is highly conserved across different species.

Function

Adenylate kinase plays a key role in the phosphotransfer network of the cell. It catalyzes the reversible transfer of a phosphate group from adenosine triphosphate (ATP) to adenosine monophosphate (AMP), producing two molecules of adenosine diphosphate (ADP):

ATP + AMP _ 2 ADP

This reaction is essential for the maintenance of cellular energy homeostasis, especially under conditions where the demand for ATP is high.

Structure

The structure of adenylate kinase consists of several domains that facilitate its function. The enzyme typically has a nucleotide-binding domain, a lid domain, and a core domain. These domains undergo conformational changes during the catalytic cycle, which are essential for its activity.

Binding of Ap5A in the active site of adenylate kinase with the arginine network labeled

Mechanism

The catalytic mechanism of adenylate kinase involves the binding of substrates to the active site, followed by a series of conformational changes that facilitate the transfer of the phosphate group. The enzyme stabilizes the transition state and lowers the activation energy of the reaction.

Kinetics

The kinetic cycle of adenylate kinase involves several steps, including substrate binding, catalysis, and product release. The enzyme exhibits Michaelis-Menten kinetics, and its activity can be regulated by various factors, including substrate concentration and allosteric regulation.

Kinetic cycle of adenylate kinase

Isoforms

There are multiple isoforms of adenylate kinase, each with specific roles and localizations within the cell. These isoforms are encoded by different genes and can be found in the cytosol, mitochondria, and other cellular compartments.

Clinical Significance

Mutations in adenylate kinase genes can lead to various metabolic disorders. The enzyme is also a target for drug development, as it plays a role in cancer metabolism and other diseases.

Related Pages

• ATP synthase
• Energy metabolism
• Enzyme kinetics
• Phosphotransferase

Gallery

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  Structure of adenylate kinase
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  Binding of Ap5A in the active site
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  Kinetic cycle