X-Pro dipeptidase

X-Pro dipeptidase, also known as prolyl dipeptidase, is an enzyme that plays a crucial role in the metabolism of proteins by catalyzing the hydrolysis of dipeptides containing a proline residue at the C-terminal position. This enzyme is classified under the EC number 3.4.13.9 and is part of the peptidase family.

Structure

Structure of X-Pro dipeptidase

X-Pro dipeptidase is a metalloenzyme, meaning it requires a metal ion for its activity. The enzyme typically contains zinc ions at its active site, which are essential for its catalytic function. The structure of X-Pro dipeptidase is characterized by a compact, globular shape, with the active site located in a cleft that allows substrate binding and catalysis.

Function

The primary function of X-Pro dipeptidase is to cleave dipeptides where the second amino acid is proline. This specificity is important because proline has a unique cyclic structure that can affect the conformation of peptides and proteins. By breaking down these dipeptides, X-Pro dipeptidase aids in the recycling of amino acids and the regulation of peptide levels within the cell.

Mechanism of Action

X-Pro dipeptidase operates through a mechanism that involves the coordination of the substrate to the zinc ion at the active site. The enzyme facilitates the nucleophilic attack on the peptide bond by a water molecule, leading to the cleavage of the bond and the release of the constituent amino acids. This process is highly specific and efficient, allowing the enzyme to process a wide range of dipeptides containing proline.

Biological Significance

X-Pro dipeptidase is found in various organisms, including bacteria, plants, and animals. In humans, it is involved in the digestion of dietary proteins and the turnover of intracellular proteins. The enzyme's activity is crucial for maintaining amino acid homeostasis and for the proper functioning of metabolic pathways that depend on proline-containing peptides.

Clinical Relevance

Alterations in the activity of X-Pro dipeptidase can have significant clinical implications. For instance, deficiencies in this enzyme may lead to the accumulation of proline-containing peptides, which can be toxic or interfere with normal cellular functions. Understanding the regulation and function of X-Pro dipeptidase is therefore important for developing therapeutic strategies for conditions associated with its dysfunction.

Related pages

• Peptidase
• Zinc metalloenzyme
• Protein metabolism