A comparison of molluscan and arthropod hemocyanin—I. Circular dichroism and absorption spectra

Abstract

1. 1. The circular dichroic (CD) spectra of molluscan and arthropod oxyhemocyanins are qualitatively and quantitatively different. 2. 2. Molluscan oxyhemocyanins have three CD bands in the visible, a positive band near 450 nm, a negative band near 570 nm and a positive band near 710 nm. 3. 3. Arthropod oxyhemocyanins have only two visible CD bands, both positive, near 490 and 610 nm. 4. 4. Both types have a negative CD band near 340 nm. 5. 5. In the region between 260–300 nm, the CD of molluscan hemocyanins is positive, that of arthropods negative. 6. 6. These data indicate fundamental differences in the oxygen binding sites of these related proteins.