The infrared spectrum and water binding of collagen as a function of relative humidity

The infrared spectra of undenatured bovine tendon collagen were investigated at 25°C and relative humidities from 0 to 95%. Suitable samples were prepared by forcing frozen suspensions of the material in distilled water through a stainless steel capillary. The samples were investigated by electron microscopy before and after the spectra were obtained to ascertain that no denaturation had taken place while the sample was exposed to infrared radiation. Temperature controlled absorption cells were constructed which permitted the passing of air with a known water content over the sample film. Gradual changes were observed in the frequencies and intensities of characteristic amide bands over the relative humidity range of 0 to 75%. These changes are particularly pronounced for the amide II band, associated with bending motions of peptide NH bonds. They lead to the conclusion that water molecules are gradually attached to peptide NH bonds within the triple helix over a wide range of relative humidity. Changes in CH deformation bands suggest that CH to O hydrogen bonding does occur and that it is more pronounced in collagen exposed to high relative humidity.     

“Jumping” satellites in three generations: A warning for paternity tests and prenatal diagnosis

Summary Identical twins with symptoms very similar to the HMC syndrome are described.