Substance P inactivating enzymes in human cerebrospinal fluid

Area of Science:

• Neurochemistry
• Enzymology
• Biochemistry

Background:

• Substance P (SP) is a neuropeptide involved in pain and inflammation.
• Understanding SP metabolism in cerebrospinal fluid (CSF) is vital for neurological research.
• Enzymatic degradation pathways of SP in human CSF remain incompletely characterized.

Purpose of the Study:

• To determine the kinetic parameters (Km and Vmax) of enzymes inactivating synthetic SP in human lumbar CSF.
• To identify the primary metabolic products of SP degradation in human CSF.
• To identify the specific enzyme responsible for SP inactivation in human CSF.

Main Methods:

• Kinetic analysis of SP degradation in human lumbar CSF samples.
• High-Performance Liquid Chromatography (HPLC) for fragment analysis.
• Electrospray Ionization Mass Spectrometry (ESI-MS) for molecular weight confirmation.

Main Results:

• Kinetic parameters for SP inactivation: Km = 2.24 ± 0.93 mM and Vmax = 0.113 ± 0.035 nmol/ml/min.
• Primary degradation product identified as SP(3-11), with minor fragments SP(1-4), SP(1-7), and SP(1-9).
• ESI-MS confirmed the molecular weights of the identified peptide fragments.

Conclusions:

• The primary enzyme responsible for synthetic SP inactivation in human lumbar CSF is a post-proline cleaving enzyme (PPCE).
• This study elucidates a key pathway in SP metabolism within the central nervous system.
• Findings contribute to understanding neuropeptide regulation and potential therapeutic targets.