Erythrocyte haemolysate interacts with ATP–Fe to form a complex containing iron, ATP and 13 800 MW polypeptide

Janet Weaver, Hui Zhan, Simeon Pollack

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Abstract

Summary Iron first entering the reticulocyte is bound to ATP in the low MW cytosolic pool; some is also ‘loosely bound’ to haemoglobin, coeluting with haemoglobin from a molecular sieve column though not incorporated into haem. When haemolysate is mixed with ATP‐Fe in vitro a similar high MW iron‐containing complex is formed: the ATP‐Fe interacts with a non‐haemoglobin constituent of the haemolysate to form a high MW ATP‐Fe complex in which the ratio of ATP:Fe (originally 6:1) is reversed, so that the complex contains more iron than ATP. The high MW ATP‐Fe complex is formed even when ATP is in 150‐fold molar excess and is formed without detectable hydrolysis of the ATP. The activity of haemolysate in forming the high MW ATP‐Fe complex is not diminished by dialysis; all of the activity is recovered in the haemoglobin‐containing fraction obtained from an Ultrogel AcA 44 column. The activity does not derive from haemoglobin since 85% of the activity is removed when haemoglobin is purified from haemolysate with DEAE‐Sephadex. The chelatable iron pool of the cell probably includes both the high MW ATP‐Fe complex and low MW ATP‐Fe. Shunting of ATP‐Fe to a high MW aggregate reduces the amount of iron present in the highly reactive low MW form and thus probably serves to limit the formation of cell damaging radicals.

Original languageEnglish (US)
Pages (from-to)138-144
Number of pages7
JournalBritish Journal of Haematology
Volume83
Issue number1
DOIs
Publication statusPublished - Jan 1993

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ASJC Scopus subject areas

  • Hematology

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