ULTIMATE COMPUTING - Quantum Consciousness Studies

172 Models of Cytoskeletal Computing
necessary to stabilize or destabilize a particular subset of microtubules for the
entire cytoskeleton to rapidly transform. Preferential stabilization of a
microtubule (MTOC, GTP capping, binding to membrane related structures etc.)
could be mediated by interactions at the cell periphery close to the site receiving
environmental information. Kirschner and Mitchison (1986) have proposed that
the dynamics of the microtubule array results in probing many regions at random
and, by stabilizing certain conformations as they arise, the cell “can arrive at a
structure that is not precisely defined by genetic information but fulfills a
particular functional role as dictated by environmental factors.” Dynamically
unstable MT offer many possibilities for controlling the distribution of MT by
selective stabilization. Kirschner and Mitchison suggest that the tendency for
probing and transformation is a fundamental advantage which favored the
evolution of dynamically active microtubules.
8.2.11 Sphere Packing Screw Symmetry/Koruga
There are 32 possible symmetry arrangements of packed spheres in a
cylindrical crystal. Erickson (1973) used hexagonal packing of protein monomers
to explain the form and patterns of viruses, flagella and microtubules. Djuro
Koruga (1986) of the University of Belgrade’s Molecular Machines Research
Unit has analyzed the symmetry laws which describe cylindrical sphere packing
and the structure of microtubules. Koruga has used both hexagonal packing and
face centered cubic packing of spheres to explain microtubule organization.
Koruga (1986):
The particular symmetry group which represents the packing of
spheres in microtubules is ‘Oh(6/4).’ Hexagonal packing may be
described by using fixed conditions if the centers of the spheres lie
on the surface of the cylinder and if the sphere values in the long
axis of the cylinder are the same as in the dimension of face centered
cubic packing. The six fold symmetry and dimer configuration lead
to screw symmetry on the cylinder: a domain may repeat by
translocating it in a spiral fashion on the cylinder. From coding
theory, the symmetry laws of tubulin subunits suggest that 13
protofilaments are optimal for the best known binary error correcting
codes with 64 code words. Symmetry theory further suggests that a
code must contain about 24 monomer subunits or 12 dimers.