A twist in chiral interaction between biological helices
نویسندگان
چکیده
Using an exact solution for the pair interaction potential, we show that long, rigid, chiral molecules with helical surface charge patterns have a preferential interaxial angle ~ RH L where L is the length of the molecules, R is the closest distance between their axes, and H is the helical pitch. Estimates based on this formula suggest a solution for the puzzle of small interaxial angles in α-helix bundles and in cholesteric phases of DNA.
منابع مشابه
Twist in chiral interaction between biological helices.
Using an exact solution for the pair interaction potential, we show that long, rigid, chiral molecules with helical surface charge patterns have a preferential interaxial angle approximately sqrt[RH]/L, where L is the length of the molecules, R is the closest distance between their axes, and H is the helical pitch. Estimates based on this formula suggest a solution for the puzzle of small inter...
متن کاملCholesterics of colloidal helices: predicting the macroscopic pitch from the particle shape and thermodynamic state.
Building a general theoretical framework to describe the microscopic origin of macroscopic chirality in (colloidal) liquid crystals is a long-standing challenge. Here, we combine classical density functional theory with Monte Carlo calculations of virial-type coefficients to obtain the equilibrium cholesteric pitch as a function of thermodynamic state and microscopic details. Applying the theor...
متن کاملPacking of Helices: Is Chirality the Highest Crystallographic Symmetry?
Chiral structures resulting from the packing of helices are common in biological and synthetic materials. Herein, we analyze the noncentrosymmetry (NCS) in such systems using crystallographic considerations. A comparison of the chiral structures built from helices shows that the chirality can be expected for specific building units such as 31/32 or 61/65 helices which, in hexagonal arrangement,...
متن کاملDirector Structures in a Chiral Nematic Slab: Threshold Field and Pitch Variations
Abstract The liquid crystal director distribution is determined for a confined chiral nematic slab. The molecular director distribution of the field-controlled chiral nematic slab is directly calculated. The director profiles for the tilt and the twist angles, under different applied fields, are calculated in the slab with weak boundary conditions. Then, the dependence of the threshold field on...
متن کاملThe geometrical origin of the strain-twist coupling in double helices
The geometrical coupling between strain and twist in double helices is investigated. Overwinding, where strain leads to further winding, is shown to be a universal property for helices, which are stretched along their longitudinal axis when the initial pitch angle is below the zero-twist angle (39.4◦). Unwinding occurs at larger pitch angles. The zero-twist angle is the unique pitch angle at th...
متن کامل