3-DIMENSIONAL RECONSTRUCTION FROM A FROZEN-HYDRATED SPECIMEN OF THE CHITON LEPIDOCHITON SP HEMOCYANIN

A frozen-hydrated specimen of the hemocyanin of the chiton Lepidochito n sp, has been subjected to a three-dimensional reconstruction by the random conical tilt- series m wall and a collar complex. The wall is c omposed of five oblique wall units, disposed as a five-stranded, right -handed helix, separated by five clefts. The oblique wall unit is comp osed 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, on e of which is connected to the wall, and an arch composed of two addit ional functional units, each connected to the wall by a narrow bridge. Each arch crosses a cleft between adjacent oblique wall units. The in dentations present on both circular faces of the molecule and the disp ositions of the masses resemble those of cephalopod hemocyanins.