Spiral Structure And The Theory Of Optical Activity Of Biological Chiral Molecules

Most of the bimolecules are chiral.In this paper we have investigated the relations between the chiral structures and their optical rotations by using theoretical calculation.Material should be determined by their structure,so as to the optical rotations of these molecules.Optical rotation,which is with the size and signs should be determined by something that also with the size and direction.Helix is the essential factor to make these materials to be optical active.Because their conformations have been changed under different conditions.The change of the helical direction in molecular structure,so that it results in change of the rotatory direction. When the changes of conditions applied to determine can not have influence on the conformation in molecular structure,the rotatory direction will not change.Optical activity is more susceptible to external factors,when measured under different conditions.It because the conformer will be different under conditions,so the helical structure will be also different,as a result of this,the optical rotations will be different,too.By using the helix theory and analyzing the stereostructure of optically active substances can be connected with the value of their mole rotation.A range of more rotation of optically active compounds can be deduced from the structure.On the basis of these theories,we have investigated the relation between the optical rotation and the helical radius and the pitch in alaninamide using density functional theory.By optimizing calculations,we obtained five stable conformers of alaninamide and their optical rotation at the computational level of B3LYP/6-311++g(2d,2p).At the same time,we also calculated radius and the pitch of these conformers.and found a relationship between optical rotation and the helical radius and the pitch.At the computational level of B3LYP/6-311++g(2d,2p),we also studied the influence of formamide(model of protein unit) on the alaninamide.We analysed structure data of formamide-alaninamide complexes and calculate the radius and the pitch of them.The results show that the changes of the geometry parameters,especially radius and pitch,have great effect on the optical rotations of each conformer and further indicated that the helix is the essential cause of the optical rotations.At last,we studied interaction between RNA segment(adenine-uracil) and model of protein unit(formamide) at the computational level of B3LYP/6-311++g(d,p).