Axial mass distributions of collagen fibrils grown in vitro: Results for the end regions of early fibrils

Abstract

The growth of native type fibrils from acetic-acid-soluble collagen has been investigated by quantitative dark-field electron microscopy. Axial mass distributions of early D-periodic fibrils were measured and expressed as plots of n a against axial position (n a is the number of molecules in a fibril cross section). Measurements were made on entire fibrils in the length range 15 D to 250 D. At the end regions of fibrils these plots were linear, with n a increasing by 4 – 5 molecules per D-period at the N-terminal end and 8 – 10 at the C-terminal. These results were not dependent on fibril length and were observed over a range of precipitating conditions.