Human proline specific peptidases: A comprehensive analysis.

Background: Proline specific peptidases (PSPs) are a unique group of enzymes that specifically cleave bonds formed by a proline residue. The study of PSPs is important due to their role in the maturation and degradation of peptide hormones and neuropeptides. In addition, changes in the activity of PSPs can result in pathological conditions, including various types of cancer.

Scope Of Review: PSPs annotated from the Homo sapiens genome were compared and classified by their physicochemical and biochemical features and roles in vital processes. In addition to catalytic activity, we discuss non-enzymatic functions that may regulate cellular activity.

Major Conclusions: PSPs apparently have multiple functions in animals. Two functions rely on the catalytic activity of the enzyme: one involved in a regulatory pathway associated with the ability of many PSPs to hydrolyze peptide hormones and neuropeptides, and the other involved in the trophic pathway associated with the proteolysis of total cellular protein or Pro-containing dietary proteins in the digestive tract. PSPs also participate in signal transduction without proteolytic activity by forming protein-protein interactions that trigger or facilitate the performance of certain functions.

General Significance: PSPs are underestimated as a unique component of the normal human peptidase degradome, providing the body with free proline. A comparative analysis of PSPs can guide research to develop inhibitors that counteract the abnormalities associated with changes in PSP activity, and identify natural substrates of PSPs that will enable better understanding of the mechanisms of the action of PSPs in biological processes and disease.