Functionally distinct haemoglobins of the cryopelagic Antarctic teleost Pagothenia borchgrevinki

Pagothenia borchgrevinki has a higher haemoglobin concentration than other Antarctic notothenioids and the high oxygen capacity may correlate with the relatively active mode of life of this fish. The fish has Eve haemoglobins (Hb C, Hb 0, Hb 1, Hb 2 and Hb 3) with I-Ib 1 accounting for 70-80% of the total, and Hb C being present in trace amounts. Hb 1 and Hb 2 are function ally similar in terms of Bohr and Root effects. Hb 3 has a weaker Bohr effe ct than Hb 1 and Hb 2, and the Root effect is similar to that of Hb 1. Hb 0 has a strong Bohr effect and the Root effect is enhanced to a larger exten t by the physiological effecters chlorides and phosphates than that of the other components with the exception of Nb C. The heats of oxygenation are l ower than those of temperate fish haemoglobins. Temperature variations may have a different effect on the functional properties of each haemoglobin, a nd chloride and phosphates may play an important role in the conformational change between the oxy and deoxy structures. The complete amino acid seque nces of Hb 1 and Hb 0, as well as partial N-terminal or internal sequences of the other haemoglobins, have been established. The high multiplicity of functionally distinct haemoglobins indicates that P. borchgrevinki has a sp ecialized haemoglobin system. (C) 2000 The Fisheries Society of the British Isles.