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Free access | 10.1172/JCI108787

Comparative Study of Protoporphyrins in Erythropoietic Protoporphyria and Griseofulvin-Induced Murine Protoporphyria: BINDING AFFINITIES, DISTRIBUTION, AND FLUORESCENCE SPECTRA IN VARIOUS BLOOD FRACTIONS

Maureen B. Poh-Fitzpatrick, Angelo A. Lamola, Gregory L. Zalar, Mark Weinstein, Frank Doleiden, and Maria Freeman

Department of Dermatology, Columbia University College of Physicians and Surgeons, New York 10032

Bell Telephone Laboratories, Murray Hill, New Jersey 07974

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Department of Dermatology, Columbia University College of Physicians and Surgeons, New York 10032

Bell Telephone Laboratories, Murray Hill, New Jersey 07974

Find articles by Lamola, A. in: PubMed | Google Scholar

Department of Dermatology, Columbia University College of Physicians and Surgeons, New York 10032

Bell Telephone Laboratories, Murray Hill, New Jersey 07974

Find articles by Zalar, G. in: PubMed | Google Scholar

Department of Dermatology, Columbia University College of Physicians and Surgeons, New York 10032

Bell Telephone Laboratories, Murray Hill, New Jersey 07974

Find articles by Weinstein, M. in: PubMed | Google Scholar

Department of Dermatology, Columbia University College of Physicians and Surgeons, New York 10032

Bell Telephone Laboratories, Murray Hill, New Jersey 07974

Find articles by Doleiden, F. in: PubMed | Google Scholar

Department of Dermatology, Columbia University College of Physicians and Surgeons, New York 10032

Bell Telephone Laboratories, Murray Hill, New Jersey 07974

Find articles by Freeman, M. in: PubMed | Google Scholar

Published August 1, 1977 - More info

Published in Volume 60, Issue 2 on August 1, 1977
J Clin Invest. 1977;60(2):380–389. https://doi.org/10.1172/JCI108787.
© 1977 The American Society for Clinical Investigation
Published August 1, 1977 - Version history
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Abstract

Excess erythrocyte protoporphyrins of human congenital erythropoietic protoporphyria and of griseofulvin-induced murine hepatic protoporphyria were found to be associated with hemoglobin and stroma fractions in similar relationships. More than 99.5% of total erythrocyte protoporphyrin was bound to hemoglobin in each case. However, profound differences were found when protoporphyrin concentration was measured in erythrocytes that had been segregated into populations of progressive age on discontinuous density gradients. In erythropoietic protoporphyria, porphyrin content diminished rapidly with age; in murine protoporphyria, the aging erythrocyte populations became progressively more porphyrin rich. In vitro diffusion of protoporphyrin from plasma across the intact erythrocyte membrane was demonstrated. The equimolar binding affinity of protoporphyrin to hemoglobin was shown to be 40 times that of protoporphyrin to serum albumin. This strong affinity provides the driving force for the observed transmembrane diffusion, and explains the high erythrocyte/plasma porphyrin ratio in murine hepatic protoporphyria. The opposite rapid efflux of intra-erythrocytic protoporphyrin into plasma previously shown in uncomplicated erythropoietic protoporphyria occurs despite this strong hemoglobin affinity, implying continuous efficient clearance of protoporphyrin from plasma by the liver. Furthermore, these and other data suggest that a hepatic synthetic source for any significant fraction of the blood protoporphyrin in erythropoietic protoporphyria is highly improbable.

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