A study of the growth of normal and iodinated collagen fibrils in vitro using electron microscope autoradiography

✍ Scribed by R. A. Haworth; J. A. Chapman

• Publisher: Wiley (John Wiley & Sons)
• Year: 1977
• Tongue: English
• Weight: 715 KB
• Volume: 16
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1977.360160906

✦ Synopsis

Abstract

Electron microscopic autoradiographic observations on collagen fibrils grown in vitro allow growth rates in the N‐ and C‐terminal directions to be measured on individual fibrils. Such observations, made on normal and iodinated collagen, show that normal fibrils grow at both ends (although rather more rapidly at the N‐terminal end), whereas fully‐iodinated collagen fibrils grow only at the N‐terminal end.

Measurements of growth rates at different temperatures provide estimates of the activation enthalpy (Δ__H__^≠^) and entropy (Δ__S__^≠^) of precipitation for the two types of collagen. Solubility measurements have also yielded values for the thermodynamic enthalpy (Δ__H__) and entropy (Δ__S__) of precipitation. Results show that the activated (rate‐limiting) state is characterized by a large positive Δ__H__^≠^ and Δ__S__^≠^ similar in magnitude to the Δ__H__ and Δ__S__ of transition from solution to fibril. It is also concluded that the different rates of precipitation of normal and iodinated collagen cannot be explained in terms of fibril formation requiring ionization of the tyrosine residues.