Diffusion of insulin-like growth factor-I and ribonuclease through fibrin gels

Biophys J. 2007 Jun 15;92(12):4444-50. doi: 10.1529/biophysj.106.102699. Epub 2007 Mar 30.

Abstract

A fluorescence-based method for simultaneously determining the diffusion coefficients of two proteins is described, and the diffusion coefficient of insulin-like growth factor (IGF-I) and ribonuclease (RNase) in a 0.27% fibrin hydrogel is reported. The method is based on two-color imaging of the relaxation of the protein concentration field with time and comparing the results with a transport model. The gel is confined in a thin (200 microm) capillary and the protein is labeled with a fluorescent dye. The experimentally determined diffusion coefficient of RNase (D = 1.21 x 10(-6) cm(2)/s) agrees with literature values for dilute gels and bulk aqueous solutions, thus indicating the gel and the dye had a negligible effect on diffusion. The experimental diffusion coefficient of IGF-I (D = 1.59 x 10(-6) cm(2)/s), in the absence of binding to the fibrin matrix, is consistent with the dimensions of the molecule known from x-ray crystallography and a correlation between D and molecular weight based on 14 other proteins. The experimental method developed here holds promise for determining molecular transport properties of biomolecules under a variety of conditions, for example, when the molecule adsorbs to the gel or is convected through the gel by fluid transport.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Computer Simulation
  • Diffusion*
  • Fibrin / chemistry*
  • Gels / chemistry*
  • Insulin-Like Growth Factor I / chemistry*
  • Models, Chemical*
  • Models, Molecular*
  • Ribonucleases / chemistry*
  • Spectrometry, Fluorescence / methods*

Substances

  • Gels
  • Insulin-Like Growth Factor I
  • Fibrin
  • Ribonucleases