Interaction of hemopexin, albumin and liver fatty acid-binding protein with protoporphyrin.
Equilibrium constants for the binding of protoporphyrin to serum albumin and hemopexin and liver cytosolic fatty acid-binding protein of the rat were determined fluorometrically. The experimental equilibrium constant [10(6) M-1 (mean +/- S.D.)] values were 8.4 +/- 1.3, 10.0 +/- 2.4 and 34.0 +/- 3.0 for albumin, hemopexin and liver fatty acid-binding protein, respectively. Statistical analysis showed the equilibrium constant of binding of protoporphyrin to liver fatty acid-binding protein to be significantly (p less than 0.01) higher than that to albumin and hemopexin. The data suggest that in patients with erythropoietic protoporphyria an equilibrium gradient may exist which favors the uptake by hepatocytes of plasma protoporphyrin as a result of its greater affinity for intracellular liver fatty acid-binding protein.
Knobler
E
E
Department of Dermatology, Columbia University College of Physicians and Surgeons, New York, New York 10032.
Poh-Fitzpatrick
M B
MB
Kravetz
D
D
Vincent
W R
WR
Muller-Eberhard
U
U
Vincent
S H
SH
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D003600:Cytosol / Q000032:analysis; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D006466:Hemopexin / Q000378:metabolism*; D008099:Liver / Q000032:analysis*; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D011166:Porphyrins / Q000378:metabolism*; D011485:Protein Binding; D011524:Protoporphyrins / Q000378:metabolism*; D051381:Rats; D012709:Serum Albumin / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
D002352:Carrier Proteins; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D011166:Porphyrins; D011524:Protoporphyrins; D012709:Serum Albumin; D006466:Hemopexin