Three-dimensional reconstruction from a frozen-hydrated specimen of the chiton Lepidochiton sp. hemocyanin.

A frozen-hydrated specimen of the hemocyanin of the chiton Lepidochiton sp. has been subjected to a three-dimensional reconstruction by the random conical tilt- series m wall and a collar complex. The wall is composed of five oblique wall units, disposed as a five-stranded, right-handed helix, separated by five clefts. The oblique wall unit is composed of two strings of functional units separated by a groove parallel with the cleft. The collar complex is a crown-like structure composed of five collar complex units, located at one end of the molecule and slightly protruding outside the cylinder wall. The collar complex unit comprises a collar unit probably composed of two functional units, one of which is connected to the wall, and an arch composed of two additional functional units, each connected to the wall by a narrow bridge. Each arch crosses a cleft between adjacent oblique wall units. The indentations present on both circular faces of the molecule and the dispositions of the masses resemble those of cephalopod hemocyanins.