The structure of Artemia sp. haemoglobins-I. Isolation and characterization of oxygen binding domains obtained by limited tryptic digestion.

Limited tryptic digestion of the extracellular haemoglobins of the crustacea Artemia sp. result in series of discrete fragments which are multiples of 16,000 d. 2. These 16,000 d fragments, together with 50,000 d and 80,000 d fragments have similar amino acid composition and tryptic peptide maps as the intact globin chains. 3. The haem content of the 16,000 d fragments is the same as this of the intact pigment and they can bind oxygen in a non cooperative way. 4. These results strongly support that the 16,000 d fragments represent structural and functional units or domains from which the globin chains are built up.