Inorganic pyrophosphatase

Inorganic pyrophosphatase (or PPase) is an enzyme that catalyzes the conversion of one molecule of pyrophosphate to two phosphate ions. This is a highly exergonic reaction, and therefore can be coupled to unfavorable biochemical transformations in order to drive these transformations to completion. The functionality of this enzyme plays a critical role in the process of DNA replication and RNA transcription.

Function

Inorganic pyrophosphatase catalyzes the hydrolysis of pyrophosphate to inorganic phosphate. This is a crucial function in the cell since the production of inorganic pyrophosphate is a byproduct of many biosynthetic reactions such as DNA replication and RNA transcription. By hydrolyzing the pyrophosphate into inorganic phosphate, the reaction is rendered irreversible. This is important in biosynthetic pathways since it ensures that the reactions proceed in the forward direction.

Structure

Inorganic pyrophosphatase is a homodimer, meaning it is made up of two identical subunits. Each subunit is composed of a five parallel alpha helix bundle and a beta sheet. The active site of the enzyme is located in the interface between the two subunits.

Clinical significance

Mutations in the gene encoding inorganic pyrophosphatase can lead to diseases such as hypophosphatasia, a rare genetic disorder characterized by the abnormal development of bones and teeth.

See also

• Pyrophosphate
• Phosphate
• DNA replication
• RNA transcription
• Hypophosphatasia

References

Inorganic pyrophosphatase Resources
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