A UNIQUE OR ESSENTIALLY UNIQUE SINGLE PARAMETRIC CHARACTERIZATION OF BIOPOLYMERIC STRUCTURES

A generalised method of characterising the three dimensional structure of any biopolymer is proposed. The method makes use of rotation and s uperposition of identical rigid monomeric units that comprise the poly mer. Out of the various parameters involved (refers the seven paramete ric representation of relating two identical rigid bodies in space), t he angle of rotation and superposition termed as 'Phi(s)', turns out t o be essentially unique. An ideal biopolymer with n identical rigid un its is characterised by (n-1) such unique angles. In applying the resu lts to real biopolymers, the importance of recognising that monomeric units are no more rigid but only quasi-rigid is emphasised. However,by appropriate choice of 'rigid' fraction of the quasi-rigid monomers, o ne is led, as first approximation, to essentially unique characterisat ion of the biopolymer with (n-1) such unique angles. The Phi(s) as a f unction of residue number acts essentially as a finger print of the gi ven polymeric fold and the conformation of the chosen biopolymer. Howe ver, the full set of seven parameters are needed for model building. I t is emphasised that the method is general in its application to any p olymer and the application of the results to proteins and nucleic acid s is illustrated.