Esterase-type of activity possessed by human plasma apolipoprotein C-II and its synthetic fragments

Petri Vainio, Jorma A. Virtanen, James T. Sparrow, Antonio M. Gotto, Paavo K.J. Kinnunen

Research output: Contribution to journalArticle

Abstract

Human plasma apolipoproteins apoA-I, A-II, C-I, C-II and C-III (with the exception of apoE), porcine pancreatic colipase and procolipase hydrolyze 4-methylumbelliferyloleate. In all cases, liberation of 4-methylumbelliferone could be inhibited by phenylmethylsulfonylfluoride, thus suggesting the involvement of serine residues. To the best of our knowledge this is the first report on the esterase activities of these peptides. Synthetic fragments of the lipoprotein lipase activator, apoC-II, prepared according to the known sequence, also possessed this esterase-type of activity. Furthermore, the esterase-type of activities of the synthetic apoC-II fragments with different chain lengths bore a relatively good correlation to the reported abilities to these peptides to produce activation of lipoprotein lipase. We propose a model for the mechanism of activation of lipoprotein lipase by apolipoprotein C-II. ApoC-II would enhance the apparent catalytic rate constant of lipoprotein lipase by functioning as a specific acyl-enzyme hydrolase. A similar catalytic mechanism is suggested for other protein co-factors of hydrolytic enzymes.

Original languageEnglish (US)
Pages (from-to)21-32
Number of pages12
JournalChemistry and Physics of Lipids
Volume33
Issue number1
DOIs
StatePublished - Jul 1983

Keywords

  • apolipoproteins
  • esterases
  • lipoprotein lipase
  • phenylmethylsulfonylfluoride
  • protein co-factors

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Organic Chemistry
  • Cell Biology

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