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Abstract: The red blood cells of the neonatal brushtailed possum exhibit unusually strong cooperativity at high levels of oxygen saturation (n =5.4) which appear to arise from a concentration dependent aggregation of one of the neonatal hemoglobin isoforms. Red blood cells from neonatal pouched young exhibit a Bohr factor of −0.36. Stripped hemolysate is sensitive to added 2,3-bisphosphoglycerate (BPG) (apparent binding constant K =35 μmol L−1) and ATP (K =180 μmol L−1), but is largely insensitive towards chloride ions. Five isoforms of non-adult hemoglobin were identified using isoelectric focusing. Mass spectrometry indicated that two early isoforms contain alpha chains identical to the adult alpha chain. The remaining three isoforms are composed of identical alpha type and beta type gene products, but differ in their isoelectric points due to differential post-translational modification. [Copyright &y& Elsevier]

Abstract: The hemoglobins contained within the red blood cells of the adult brushtail possum exhibited cooperative (n =2.6) oxygen binding curves with an associated p50 of 38 mm Hg at pH 7.4 and a large Bohr effect (−0.60). Stripped hemolysate showed a Bohr effect of −0.27, and was sensitive to added DPG (K =56 μmol L−1), ATP (K =130 μmol L−1), and chloride ions. Four isoforms of hemoglobin were identified using isoelectric focusing. Mass spectrometry indicated that all four isoforms most likely represent the same gene products which have differentially undergone post-translational deamidation and glutathionylation. The oxygen binding characteristics of three isolated isohemoglobins have been determined. [Copyright &y& Elsevier]