Structural diversity of arthropod extracellular haemoglobins

1. 1. Extracellular haemoglobins from several arthropod species were investigated by sedimentation in the ultracentrifuge and sodium dodecyl sulfate gel electrophoresis. 2. 2. Haemoglobins from Lepidurus apus (19.3S), Daphnia sp. (17.6S) and Cyzicus hierosolymitanus (11.4S) are each composed of many identical polypeptide chains (mol. wt 34,000, 31,000 and 30,000 daltons respectively). Streptocephalus haemoglobin (11.4S) is composed of two, maybe three, similar polypeptide chains (mol. wt 100,000-120,000 daltons). Chironomus larval haemoglobins are composed of one, sometimes of two, polypeptide chains (mol. wt ca. 16,000 daltons). 3. 3. Arthropod haemoglobins exhibit structural diversity. Classification of the haemoglobins on the basis of their molecular structure places the species in categories in accordance with their taxonomical groupings.