Neurochemical Research

, Volume 18, Issue 7, pp 743–749

Purification and characterization of tripeptidylpeptidase-II from post-mortem human brain

  • C. Wilson
  • A. M. Gibson
  • J. R. McDermott
Original Articles

DOI: 10.1007/BF00966768

Cite this article as:
Wilson, C., Gibson, A.M. & McDermott, J.R. Neurochem Res (1993) 18: 743. doi:10.1007/BF00966768

Abstract

A soluble tripeptidylaminopeptidase has been isolated from human post-mortem cerebral cortex by anion exchange, hydrophobic interaction and size-exclusion chromatography. From gel filtration studies the active enzyme can exist in both high molecular weight (Mr>106) and smaller forms. The enzyme hydrolyses Ala-Ala-Phe-7-amino-4-methylcoumarin with a pH optimum of around 7.5 and Km of 148 μM. It did not hydrolyse N-succinyl-Ala-Ala-Phe-7-amino-4-methylcoumarin, aminoacyl- or dipeptidyl-7-amino-methylcoumarins and was not inhibited by bestatin. The enzyme was inhibited by phenylmethylsulphonyl-fluoride, 3,4-dichloroisocoumarin, N-hydroxymercuriphenyl-sulphonic acid and N-ethylmaleimide showing that its activity is serine and cysteine dependent. The purified enzyme released tripeptides from several naturally occurring neuropeptides with quite broad specificity. Cholecystokinin octapeptide, angiotensin III and neurokinin A were the most rapidly hydrolysed. Peptides with Pro residues arount the point of cleavage were not hydrolysed.

Key words

Tripeptidylpeptidase aminopeptidase neuropeptides human brain cholecystokinin octapeptide neurokinin-A 

Copyright information

© Plenum Publishing Corporation 1993

Authors and Affiliations

  • C. Wilson
    • 1
  • A. M. Gibson
    • 1
  • J. R. McDermott
    • 1
  1. 1.MRC Neurochemical Pathology UnitNewcastle General HospitalNewcastle upon TyneUK