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Binding affinity and reactivity of lecithin cholesterol acyltransferase with native lipoproteins.

Authors
  • Kosek, A B
  • Durbin, D
  • Jonas, A
Type
Published Article
Journal
Biochemical and biophysical research communications
Publication Date
May 19, 1999
Volume
258
Issue
3
Pages
548–551
Identifiers
PMID: 10329423
Source
Medline
License
Unknown

Abstract

The first step in the reaction of lecithin cholesterol acyltransferase (LCAT) with lipoproteins is the interfacial binding of the enzyme to the lipid surfaces. In this study the equilibrium dissociation constants (Kds) for the interaction of pure human plasma LCAT with LDL, HDL2, HDL3, and a reconstituted discoidal HDL (rHDL) were determined by the activity-inhibition method. In addition, enzyme kinetics were measured with each of the lipoprotein substrates. Based on phospholipid concentrations, the Kd values (0.9 x 10(-5) to 4.6 x 10(-5) M) increased in the order rHDL = HDL3 </= HDL2 < LDL while the relative reactivities (app Vmax/app Km) with LCAT were 100, 16, 1, 6%, respectively, for the different lipoproteins. These quantitative measures were used to predict the distribution of LCAT in plasma and to explain cholesterol esterification when HDL are absent or ineffective as substrates.

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