Partial Primary Structure of the Helix Pomatia ßc-Hemocyanin Functional Unit D

Hemocyanins occur in two different phyla: molluscs and arthropods. Although their physiological role and some spectroscopic properties are similar, their quaternary structure and arrangement of oxygen binding units show great differences. The evolutionary relationship between both hemocyanin classes can only be solved by comparing their amino acid sequences. The first two sequences of arthropodan subunits were published in 1983 (1,2) and more data have since become available (3,4). Here we report the nearly complete amino acid sequence of domain d of Helix pomatia sc hemocyanin, which allows for the first time a direct comparison of molluscan and arthropodan hemocyanin structures.