Studies on the Interaction of Organic Phosphates with Haemoglobin in an Amphibian (Bufo marinus), a Reptile (Trachydosaurus rugosus) and Man

Abstract

The primary organic phosphate modifiers of haemoglobin function are DPG (2,3-diphosphoglycerate) in the toad Bufo marinus and ATP in the lizard Trachydosaurus rugosus. Myo-IP6 (myoinositol hexaphosphate) and myo-IPs (myo-inositol pentaphosphate) are more effective than ATP or DPG in reducing the oxygen affinities of the haemoglobins of B. marinus, T. rugosus and man, while ATP and DPG are about equally effective. Competition experiments indicate that ATP, DPG and myo-IP6 bind to the same site or sites on the haemoglobins of each of the species. These findings, and those of others, are interpreted as evidence that the evolution of an organic phosphate binding site on the haemoglobin of an ancient vertebrate pre-adapted haemoglobin for interaction with a set of organic phosphates having certain structural features in common.