The precipitation of toroidal collagen fibrils.
The morphology of aggregates of calf-skin tropocollagen, precipitated by continuous injection into neutral phosphate buffers at 35 degrees , has been studied by electron microscopy. Although most of the collagen is precipitated as normal native fibrils, a small proportion forms closed toroidal structures having the usual native band-interband pattern. Theoretical considerations, based on elastic energies in a general microfibril model, predict that the toroids should have a simple super-helical structure, and this is not inconsistent with the observations. From the theoretical energies it was possible to estimate a crude lower limit of 3kcal./mole for the free energy of association of the tropocollagen macromolecules.
D000818:Animals; D002021:Buffers; D002417:Cattle; D055598:Chemical Phenomena; D011232:Chemical Precipitation; D002621:Chemistry; D003094:Collagen; D008854:Microscopy, Electron; D012867:Skin / Q000166:cytology; D013816:Thermodynamics
D002021:Buffers; D003094:Collagen