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A study of the growth of normal and iodinated collagen fibrils in vitro using electron microscope autoradiography
Author(s) -
Haworth R. A.,
Chapman J. A.
Publication year - 1977
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1977.360160906
Subject(s) - fibril , chemistry , enthalpy , electron microscope , precipitation , collagen fibril , solubility , crystallography , scanning electron microscope , ionization , in vitro , biophysics , thermodynamics , biochemistry , organic chemistry , materials science , ion , physics , biology , meteorology , optics , composite material
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.