. Aspects of the origin of life. Life; Biochemistry; Biochemistry; Biogenesis. 160 J. D. BERNAL A co-ordination number of two leads to an unbranched linear association. If the two co-ordinating are nearly at i8o° the result is a nearly straight line polymer of indefinite length; if the angle is smaller it is a ring or close helix. Angles of 90° or less will produce fourfold or triple aggregations without much waste space, as for instance in the 33,000 mol. wt unit in zinc insuUn. The helix will be the most probable form for larger angles owing to the stabilizing effect of secondary interaction
. Aspects of the origin of life. Life; Biochemistry; Biochemistry; Biogenesis. 160 J. D. BERNAL A co-ordination number of two leads to an unbranched linear association. If the two co-ordinating are nearly at i8o° the result is a nearly straight line polymer of indefinite length; if the angle is smaller it is a ring or close helix. Angles of 90° or less will produce fourfold or triple aggregations without much waste space, as for instance in the 33,000 mol. wt unit in zinc insuUn. The helix will be the most probable form for larger angles owing to the stabilizing effect of secondary interactions between successive coils. This seems to be the explanation for the arrangement of the protein shell in the rod-like viruses such as tobacco mosaic virus, though we cannot be sure yet whether in this case there is one closely packed helix or an aggregation of several sUghtly coiled heUces. The simplest form of three co-ordinated pattern is that of a hexagonal plane net. This, however, imless stabilized, is hkely to curl into a cylinder or spiral roll. At any rate no indisputable example of it has been analysed though it may account for the protein part of cellular or intracellular membranes. Another product of three co-ordination is the closed basket of cubic, often of isoctahedral, symmetry (532) which has been revealed as the shell of the globular viruses—. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Florkin, Marcel; International Symposium on the Origin of Life on Earth (1957 : Moscow). Proceedings. Oxford, New York, Pergamon Press
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