THE BLOOD PROTEINS OF THE ANTARCTIC ICEFISH CHANNICHTHYS-RHINOCERATUS- BIOLOGICAL SIGNIFICANCE AND PURIFICATION OF THE 2 MAIN COMPONENTS

The lack of hemoglobin and of carbonic anhydrase in the blood of icefi sh suggest that substantial adaptations of the acid-base balance shoul d occur in order to ensure blood pH homeostasis. The level of peptidic histidyl and of reactive -SH groups per unit of body mass in icefish plasma are 12-13 times higher that those of Notothenia rossii, a commo n red-blooded Antarctic species. It is proposed that the high level of imidazole ring in icefish plasma improves the non-bicarbonate bufferi ng capacity and that the reactive sulfhydryls are involved om a redox buffer as in some other hypoxia tolerant species. After plasma fractio nation on Ultrogel AcA 34, the two main icefish serum proteins have be en purified by DEAE cellulose chromatography (IFI) and by HPLC on anio n exchange column (IF2). IFI has been identified as a cysteine-rich pa ra-albumin and IF2 as an histidine-rich immunoglobulin-like protein.