Carbon dioxide governs the oxygen affinity of crocodile blood

Chiristian Bauer*, Wolfgang Jelkmann

*Corresponding author for this work
42 Citations (Scopus)


OXYGEN affinity of haemoglobin inside red blood cells is decreased to a level where oxygen unloading can proceed at sufficiently high partial pressures in the tissue capillaries. This adaptation of oxygen affinity is accomplished mainly by the interaction of haemoglobin with intraerythrocytic phosphates 1. These comprise 2,3-diphosphoglycerate (DPG) in most mammals, ATP and GTP in fish2, and myo-inositol pentaphosphate (IP5) in mature birds3-5. No haemoglobin system has been described in higher vertebrates which is devoid of functional interaction with the respective intracellular phosphates. Recently, however, Sullivan6 has questioned the role of phosphates for the control of oxygen affinity in crocodilered cells (ATP and inorganic phosphate have been identified3,7,8). He remarks that 'the substance regulating oxygen affinity in alligators is very efficient, but unknown'. We show here that the oxygen affinity of haemoglobin from a member of the order crocodiles (Crocodylus porosus) is not affected by any of the regulating allosteric cofactors known with the exception of molecular CO 2 and protons.

Original languageEnglish
Issue number5631
Pages (from-to)825-827
Number of pages3
Publication statusPublished - 1977

Research Areas and Centers

  • Academic Focus: Center for Brain, Behavior and Metabolism (CBBM)


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