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The egress of oxygen from human HbO 2 in solution and in the erythrocyte
Author(s) -
Sirs John A.
Publication year - 1967
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1967.sp008179
Subject(s) - oxygen , dilution , chemistry , dissociation (chemistry) , carbon monoxide , suspension (topology) , analytical chemistry (journal) , chromatography , biophysics , biochemistry , thermodynamics , organic chemistry , physics , mathematics , homotopy , biology , pure mathematics , catalysis
1. Spectrophotometric measurements, using the rapid‐mixing constantflow and stopped‐flow techniques, have been made of the rate of egress of oxygen from human HbO 2 in solution and in erythrocytes. 2. By 1:20 dilution in a medium containing a high concentration of carbon monoxide k 4 , the rate constant of the reaction Hb 4 O 8 → Hb 4 O 6 +O 2 has been determined. At pH 7·4 and 20° C, k 4 in solution was 42·0 sec −1 and within the intact cell 41·4 sec −1 . The respective activation energies were 19·3 and 18 kcal. 3. The rate of dissociation of HbO 2 to Hb, after mixing an erythrocyte suspension with Na 2 S 2 O 4 , was identical, over at least 50% of the reaction, with the change of HbO 2 to HbCO above. 4. An analysis of the data indicates that the cell membrane has little or no resistance to the passage of oxygen and the internal contents are effectively mixed.