Liquid crystallinity in collagen solutions and magnetic orientation of collagen fibrils

Studies of the optical birefringence of solutions of acid‐soluble collagen from rat‐tail tendon at 22°C in the pH range 1.0–6.0 show that collagen exhibits an isotropic to mesophase transition only between pH 2.4 and 3.0 at 10% weight concentration. Such liquid crystalline order is probably essential for the orientation of collagen in a magnetic field. When solutions of neutral salt‐soluble collagen were precipitated at pH 7.0 by warming to 37°C (“heat gelling”) in a magnetic field of ca. 20 kG, the resulting fibrils wee oriented perpendicular to the direction of the field. Heat gelling is shown to be a useful technique for maintaining the orientation induced in precursor solutions even after the sample is removed from the magnetic field.

[1]  J. Gross,et al.  The heat precipitation of collagen from neutral salt solutions: some rate-regulating factors. , 1958, The Journal of biological chemistry.

[2]  R. Trelstad,et al.  Collagen fibrillogenesis: intermediate aggregates and suprafibrillar order. , 1976, Proceedings of the National Academy of Sciences of the United States of America.

[3]  Ioannis V. Yannas,et al.  Collagen and Gelatin in the Solid State , 1972 .

[4]  C. T. O'konski,et al.  Electric properties of macromolecules. IX. Dipole moment, polarizability, and optical anisotropy factor of collagen in solution from electric birefringence , 1966, Biopolymers.

[5]  L. Onsager.  THE EFFECTS OF SHAPE ON THE INTERACTION OF COLLOIDAL PARTICLES , 1949 .

[6]  G. H. Brown.  Advances in Liquid Crystals , 1976 .

[7]  D. Hulmes,et al.  Quasi-hexagonal molecular packing in collagen fibrils , 1979, Nature.

[8]  P. Flory,et al.  Statistical thermodynamics of semi-flexible chain molecules , 1956, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[9]  B. Roux,et al.  Electrical birefringence study of monodisperse collagen solutions , 1974, Biopolymers.

[10]  David W.L. Hukins,et al.  Collagen Fibrils as Examples of Smectic A Biological Fibres , 1977 .

[11]  H. Boedtker,et al.  A Study of Gelatin Molecules, Aggregates and Gels , 1954 .

[12]  Fracture of tendon collagen , 1972 .

[13]  P. Flory,et al.  Phase equilibria in solutions of rod-like particles , 1956, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[14]  G. Maret,et al.  Local order in polyelectrolytic solutions detected by magnetic birefringence measurements on the (Tyr‐Glu)n copolymer , 1979 .

[15]  D. Worcester,et al.  Structural origins of diamagnetic anisotropy in proteins. , 1978, Proceedings of the National Academy of Sciences of the United States of America.

[16]  G. Martin,et al.  Subunits of the collagen molecule. , 1961, Biochimica et biophysica acta.