Open AccessBinding of Magnesium and Chloride Ions to Human Hemoglobin A
Author(s) -
ACHILLES Wolfgang,
CUMME Gerhard A.,
WINNEFELD Klaus,
FRUNDER Horst
Publication year - 1981
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1981.tb05738.x
Subject(s) - hemoglobin , chemistry , deoxygenation , ultrafiltration (renal) , mole , magnesium , chloride , inorganic chemistry , ion , nuclear chemistry , chromatography , biochemistry , catalysis , organic chemistry
Ultrafiltration and direct determination of [Mg 2+ ]by ion exchange were used to study the binding of Mg 2+ and Cl − to isoionic human hemoglobin A value of 58.8+1.71/mol was determined for the volume of hydrated hemoglobin from ultrafiltration of hemoglobin solutions containing 0.15–0.8 M glucose. In solutions with 5.7 mmol hemoglobin,150mmol KCl and 0.5–3.5 mmol MgCl 2 /l total water,0.6 mol and 2 mol cl − were bound/mol oxygenated and deoxygenated hemoglobin respectively. A value of about 111/mol was determined for the association constant of Mg 2= to hemoglobin monomer. Free Mg 2+ concentrations were measured in hemoglobin solutions containing KCl, MgCl 2 , ATP and d ‐ glycerate‐2.3‐bisphosphate at concentrations close to those of red cells. The experiments yielded 0.65 mmol/l free Mg 2+ after oxygenation and 0.82 mmol/l after deoxygenation.The data indicate that only small changes of free Mg 2+ levels in red cells are caused by physiological changes of p O 2 .