Differential scanning calorimetry (DSC) and thermally stimulated current (T
SC) were used to characterize human-bone collagen. DSC glass-transition and
denaturation temperatures of the collagen in a dehydrated state were 90 an
d 215 degrees C, respectively. By TSC, the main relaxation mode, labeled a
and located around 90 degrees C, could be attributed to the dielectric mani
festation of the glass transition. The corresponding molecular movements ar
e cooperative with a compensation temperature close to the denaturation tem
perature. At low temperatures and in a hydrated state, a second mode labele
d beta(2) was observed at -110 degrees C. Dehydration shifted this mode to
higher temperatures, revealing a weak mode labeled gamma at -150 degrees C.
This gamma mode was attributed to motions of aliphatic side chains. An ana
lysis of low-temperature elementary spectra allowed us to assign the beta(2
) mode to structural water movements and revealed an additional compensatio
n phenomenon in the temperature range (-80 to -50 degrees C). Because the c
ompensation temperature of this mode was close to the collagen glass-transi
tion temperature, the corresponding mode beta(1) was attributed to polar si
de-chain motions, precursors of a collagen glass transition. Finally, aroun
d ambient temperature, three sharp peaks were attributed to hydrogen bonds
breaking. (C) 2000 John Wiley & Sons, Inc.