Inhibition of phosphatidylinositol-specific phospholipase C: Studies on synthetic substrates, inhibitors and a synthetic enzyme

Dragos Vizitiu, Angela G. Kriste, A. Stewart Campbell, Gregory R.J. Thatcher

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Enzyme inhibition studies on phosphatidylinositol-specific phospholipase C (PI-PLC) from B. Cereus were performed in order to gain an understanding of the mechanism of the PI-PLC family of enzymes and to aid inhibitor design. Inhibition studies on two synthetic cyclic phosphonate analogues (1,2) of inositol cyclic. 1:2-monophosphate (cIP), glycerol-2-phosphate and vanadate were performed using natural phosphatidylinositol (PD substrate in Triton X100 co-micelles and an NMR assay. Further inhibition studios on PI-PLC from B. Cereus were performed using a chromogenic, synthetic PI analogue (DPG-PI), an HPLC assay and Aerosol-OT (AOT), phytic acid and vanadate as inhibitors. For purposes of comparison, a model PI-PLC enzyme system was developed employing a synthetic Cu(II)-metallomicelle and a further synthetic PI analogue (IPP-PI). The studies employing natural PI substrate in Triton XI00 co-micelles and synthetic DPG-PI in the absence of surfactant indicate three classes of PI-PLC inhibitors: (1) active-site directed inhibitors (e.g. 1,2); (2) water-soluble polyanions (e.g. tetravanadate, phytic acid); (3) surfactant anions (e.g. AOT). Three modes of molecular recognition are indicated to be important: (1) active site molecular recognition; (2) recognition at an anion-recognition site which may be the active site, and; (3) interfacial (or hydrophobic) recognition which may be exploited to increase affinity for the anion-recognition site in anionic surfactants such as AOT. The most potent inhibition of PI-PLC was observed by tetravanadate and AOT. The metallomicelle model system was observed to mimic PI-PLC in reproducing transesterification of the PI analogue substrate to yield cIP as product and in showing inhibition by phytic acid and AOT.

Original languageEnglish (US)
Pages (from-to)197-209
Number of pages13
JournalJournal of Molecular Recognition
Volume9
Issue number2
DOIs
StatePublished - Mar 1996
Externally publishedYes

Keywords

  • inositol
  • me tallomicelle
  • phosphatidylinositol
  • phospholipase
  • phosphotransferase
  • surfactant

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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