ULTIMATE COMPUTING - Quantum Consciousness Studies

132 Protein Conformational Dynamics
Figure 6.2: Alpha helix with three “spines” formed by hydrogen bonds (dashed
lines) between hydrogen and oxygen atoms. With permission from Bolterauer,
Henkel and Opper (1986).
Each distinct conformation of an allosteric protein has a different surface and
a different ability to interact with other binding molecules or “ligands.” Only one
of several conformations may have a high affinity for a particular ligand and the
presence or absence of that ligand can determine the conformation that the protein
adopts. Two distinct ligands may bind specifically to different surfaces of the
same protein, so that the concentration of one ligand may change the affinity of
the protein for the other. Such allosteric mechanisms facilitate fine tuning and
regulation of many biological processes in which proteins transduce, or integrate
various modes of signaling and information. Allosteric proteins are especially
effective signaling devices when they exist as aggregates of identical subunits.
The conformation of one subunit can influence that of neighboring subunits,
producing a collective effect similar to amplification or switching in a computer.
The collective behavior of hemoglobin in its binding of oxygen is one example;
state transformations in microtubules may be another.
The conformational state of a specific protein is regulated by a variety of
factors and may have profound importance for functional activity. Hemoglobin is