A Refined Quaternary Structure of <em>Androctonus australis</em> Hemocyanin.

The quaternary structure of the (4 &#215; 6)-mer hemocyanin from the scorpion Androctonus australis previously published [Lamy. J., Bijiholt. M. M. C. Sizaret, P.-Y., Lamy. J., and van Bruggen. E. F. J. (1981) Biochemistry, 20, 1849-1856] has been refined. The relative positions in the half molecule of subunits Ac 3A and Ac 38 compared to those of Aa 3C and Aa 58 have been established by double labeling of the (2 &#215; 6)-mer with binary mixtures of subunit-specific Fab fragments. The results show that subunits Ac, 38 and Ac, 58 are located in the same hexamer while Aa 3A and Au 3C are in the other half of the (2 &#215; 6)-mer. The choice of the enantiomer was deduced from a careful examination of&#39; electron micrographs of the native molecule. Finally a position was assigned to each of the 24 subunits on the flip and flop faces as defined by Van Heel and Frank [Ultramicroscops, 6, 187-194 (1981)]. [ABSTRACT FROM AUTHOR]