PAF-acetylhydrolase, predominantly present in LDL in healthy subjects, is associated with HDL in a patient with LDL deficiency.
The degradation of platelet-activating factor (PAF) in plasma is catalyzed by PAF-acetylhydrolase resulting in lyso-PAF which is biologically inactive. Normally, most of the PAF-degrading activity is associated with low-density lipoproteins (LDL). The enzyme activity was measured in the plasma of a patient with abetalipoproteinemia, a disorder characterized by the absence of apolipoprotein-B-containing lipoproteins (chylomicrons, VLDL and LDL). Here we report that the plasma of the patient has a normal activity of PAF-acetylhydrolase. The enzyme activity is bound to high-density lipoproteins (HDL) and shows the kinetic properties of the LDL-associated enzyme of healthy subjects. Following administration of artificial triglyceride-rich particles (ATRP), part of the enzyme activity is found associated with ATRP, indicating that PAF-acetylhydrolase can transfer from HDL to triglyceride-containing lipid complexes in vivo.
Surya
I I
II
Department of Hematology, University Hospital Utrecht, The Netherlands.
Mommersteeg
M
M
Erkelens
D W
DW
Akkerman
J W
JW
D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D000012:Abetalipoproteinemia / Q000201:enzymology*; D000328:Adult; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007700:Kinetics; D008075:Lipoproteins, HDL / Q000737:chemistry*; D008077:Lipoproteins, LDL / Q000737:chemistry*; D010741:Phospholipases A / Q000097:blood*; D012016:Reference Values; D014280:Triglycerides / Q000494:pharmacology
D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D014280:Triglycerides; D010741:Phospholipases A; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase