Allosteric enzyme

From WikiMD's Wellness Encyclopedia

Allosteric enzyme is a type of enzyme that changes its conformational ensemble upon binding of an effector, resulting in an apparent change in binding affinity at a different ligand binding site. This modification can either enhance or inhibit the enzyme's activity, providing a means to regulate its function.

Overview[edit | edit source]

Allosteric enzymes are a key component in biochemical pathways, playing a crucial role in metabolism and cellular regulation. They are characterized by their ability to bind to specific molecules, known as effectors or allosteric modulators, at a site other than their active site. This binding induces a conformational change in the enzyme, altering its activity.

Mechanism[edit | edit source]

The mechanism of allosteric regulation is based on the induced fit model of enzyme-substrate interaction. When an allosteric modulator binds to the enzyme, it induces a change in the enzyme's shape. This change can either increase or decrease the enzyme's affinity for its substrate, thereby modulating its activity.

Types of Allosteric Regulation[edit | edit source]

There are two main types of allosteric regulation: positive and negative. Positive allosteric regulation occurs when the binding of the modulator increases the enzyme's activity, while negative allosteric regulation occurs when the binding decreases the enzyme's activity.

Examples[edit | edit source]

One of the most well-known examples of an allosteric enzyme is hemoglobin, a protein that transports oxygen in the blood. Hemoglobin's affinity for oxygen is increased when an oxygen molecule binds to one of its subunits, a phenomenon known as cooperative binding.

Another example is the enzyme phosphofructokinase, which plays a key role in the regulation of glycolysis. This enzyme is inhibited by high levels of ATP, an example of negative allosteric regulation.

See Also[edit | edit source]

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Contributors: Prab R. Tumpati, MD