Comparison of chlorocruorin and annelid hemoglobin quaternary structures

1. 1. The structures of Eudistylia vancouveri chlorocruorin and Pista pacifica and Thelepus crispus extracellular hemoglobins have been examined by electron microscopy. The intact pigments display a two-tiered hexagonal array characteristic of other annelid high molecular weight hemoglobins and chlorocruorins. 2. 2. The smallest subunit molecular weight of these pigments determined by SDS gel electrophoresis is 14–15,000; Pista hemoglobin contains some additional 30,000 molecular weight material under a variety of denaturing conditions. Earthworm hemoglobin is also heterogenous upon SDS gel electrophoresis, consisting of at least six components with mol. wt ranging from 13, 000 to 35,000. 3. 3. The amino acid compositions of these high molecular weight pigments are compared with one another and with the intracellular hemoglobins of other invertebrates and vertebrates. It is likely that Eudistylia chlorocruorin and certain high molecular weight annelid hemoglobins form a group of closely related proteins.