Structure and properties of hemocyanins: III. Electron micrographs of hemocyanins from different gastropoda and crustacea

Abstract

Electron micrographs of negatively stained hemocyanin molecules of some Gastropoda (Helix pomatia, Buccinum undatum and Neptunea antiqua) and some Crustacea (Palinurus vulgaris, Homarus vulgaris, Nephrops norvegicus, Cancer pagurus and Carcinus maenas) were made. With the Gastropoda the molecular structure and dissociation at the alkaline side of the isoelectric point have been studied. Differences are observed between Helix p. and Buccinum u. on one hand and Neptunea a. on the other. The electron micrographs suggest that the first two hemocyanins are built from six equidistant parallel layers of subunits, while the latter consists of three double-layers of subunits. This makes a dissociation via half molecules highly improbable for Neptunea hemocyanin and thus explains the absence of the corresponding component on the sedimentation patterns. The molecular structures of the 16 s and 23 s component of the Crustacea hemocyanins were studied. The observed projections of the 16 s component are compatible with a molecular model consisting of eight subunits lying on the corners of a cube. The 23 s component is a dimer of two of these cubes.