Abstract
Abstract : In thalassemia Heins bodies are held responsible for damage to the red cell membrane and premature hemolysis. Relatively little is known however about the biochemical membrane alterations.
We investigated in various types of beta-thalassemias the kinetics of a neutral membrane bound phosphatase,using purified red cell ghosts and para-nitrophenyl phosphate (pNPP) as the substrate (the apparent Michaelis enten constant for pNPP is 2,5 mM).In two related cases of beta-thalassemia, the kineti cs of the ensyme,instead of beeing of the Michaelis Menten type displayed a biphasic aspect.Simple reciprocal plots (reciprocal velocity vs pNPP concentration) were consistent with a pure inhibi tion process by substrate excess. KI app ranged from 18 to 35 mM. In three unrelated cases of beta-plus thalassemia the kinetios were essentially of the Michaelis-Menten type for two patients and of an intermediate type for the third one.
A 35% depletion of the membrane cholesterol obtained by incubation of the ghodts with phosphatidylcholine vesicles did not alter the abnormal kinetics,although it decreased the velocity in both beta-zero thalassemia cases.We assume some change in the enzyme hydrophobic environment, different from a cholesterol content decrease.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Morle, F., Delaunay, J., Morle, L. et al. Abnormal red cell membrane phosphatase activity in Beta-thalassemia. Pediatr Res 14, 1425 (1980). https://doi.org/10.1203/00006450-198012000-00104
Issue Date:
DOI: https://doi.org/10.1203/00006450-198012000-00104