Peptidomics of Prolyl Endopeptidase in the Central Nervous System

Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
Biochemistry (Impact Factor: 3.02). 11/2009; 48(50):11971-81. DOI: 10.1021/bi901637c
Source: PubMed


Prolyl endopeptidase (Prep) is a member of the prolyl peptidase family and is of interest because of its unique biochemistry and connections to cognitive function. Using an unbiased mass spectrometry (MS)-based peptidomics platform, we identified Prep-regulated peptides in the central nervous system (CNS) of mice by measuring changes in the peptidome as a function of Prep activity. This approach was validated by the identification of known Prep substrates, such as the neuropeptide substance P and thymosin-beta4, the precursor to the bioactive peptide Ac-SDKP. In addition to these known substrates, we also discovered that Prep regulates many additional peptides, including additional bioactive peptides and proline rich peptides (PRPs). Biochemical experiments confirmed that some of these Prep-regulated peptides are indeed substrates of the enzyme. Moreover, these experiments also supported the known preference of Prep for shorter peptides while revealing a previously unknown cleavage site specificity of Prep when processing certain multi-proline-containing peptides, including PRPs. The discovery of Prep-regulated peptides implicates Prep in new biological pathways and provides insights into the biochemistry of this enzyme.

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    • "In the study of Nolte et al. [21], the peptides that were found to be elevated by PREP inhibition in mice brain were longer and contained more prolines than typical PREP substrates. Notably, the majority of the peptides identified as possible PREP substrates in these two studies contained an internal proline, thus supporting the role of PREP in the catabolism of proline-containing peptides in vivo. "
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