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Kinetic Anomalies Associated with Phospholipase A2 Hydrolysis of Micellar Substrates

  • Thomas T. Allgyer
  • Michael A. Wells
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 101)

Abstract

It is well known that Phospholipase A2 hydrolyzes micellar substrates at considerably faster rates than monomeric substrates. The origin of this interfacial activation is a subject of considerable importance in understanding the mechanism of action of lipolytic enzymes. Crotalus adamanteus Phospholipase A2 exhibits “normal” Michaelis kinetics with monomeric substrates (12) and with micellar substrates at concentrations well above the critical micelle concentration (cmc) (13). However, at concentrations near the cmc anomalous velocity vs substrate concentration plots are observed which are parabolic rather than hyperbolic (11, 13). We have noted this phenomenon for several different substrates and for Phospholipases A2 from various sources and for cabbage Phospholipase D, and have empiricially determined that such anomalous regions give linear plots of v1/2 vs substrate concentration. To our knowledge no satisfactory explanation for these anomalous regions have been presented. The purpose of this paper is to explore various explanations for this behavior and to propose a model for substrate micellization which satisfactorily predicts such anomalous kinetics.

Keywords

Critical Micelle Concentration Micelle Formation Polar Head Group Anomalous Region Oblate Ellipsoid 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    Cohen, H., Shen, B.W., Snyder, W.R., Law, J.H., and Kèzdy,F.J. (1976): J. Colloid Interface Sci 56; 240–250.CrossRefGoogle Scholar
  2. 2.
    Hershberg, R.D., Reed, G.H., Slotboom, A.J., and de Haas, G.H. (1976): Biochim. Biophys. Acta 424: 73–81.PubMedCrossRefGoogle Scholar
  3. 3.
    Llerenas, E., and Mingins, J. (1976): Biochim. Biophys. Acta 112: 381–384.Google Scholar
  4. 4.
    Pieterson, W.A. (1973): Thesis, Rijksuniversiteit, Utrecht.Google Scholar
  5. 5.
    Taylor, J.A.G., Mingins, J., Pethica, B.A., Tan, B.Y.J., and Jackson, C.M. (1973): Biochim. Biophys. Acta 323: 157–160.PubMedCrossRefGoogle Scholar
  6. 6.
    Tanford, C. (1974):. J. Plays. Chem 78: 2469–2479.CrossRefGoogle Scholar
  7. 7.
    Tanford, C. (1974): Proc. National Acad. Sci. U.S.A 71: 1811–1815.CrossRefGoogle Scholar
  8. 8.
    Tausk,.R.J.M., Karmiggelt, J., Oudshoorn, C., and Overbeek, J. (1974): Biophysical Chem. 1: 175–183.CrossRefGoogle Scholar
  9. 9.
    Tausk, R.J.M., van Esch, J, Karminggelt, J., Voordouw, G., and Overbeek, J. Th.G. (1974): Biophysical Chem. 1: 184–203.CrossRefGoogle Scholar
  10. 10.
    Tausk, R.J.M., Oudshoorn, C., and Overbeek, J.Th.G. (1974): Biophysical Chem. 2: 53–63.CrossRefGoogle Scholar
  11. 11.
    Verger, R., and deHaas, G.H. (1976): Ann. Rev. Biophysics Bioengineering, 5: 77–117.CrossRefGoogle Scholar
  12. 12.
    Wells, M.A. (1973):. Biochemistry 12: 1030–1041.Google Scholar
  13. 13.
    Wells, M.A. (1974): Biochemistry 13: 2248–2257.PubMedCrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1978

Authors and Affiliations

  • Thomas T. Allgyer
    • 1
  • Michael A. Wells
    • 1
  1. 1.Biochemistry DepartmentCollege of Medicine University of ArizonaTucsonUSA

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