  Vibrational spectroscopy has been widely employed to unravel
physical-chemical properties of biological systems. Due to its high sensitivity
to monitor real time "in situ" changes, Raman spectroscopy has been
successfully employed, e.g., in biomedicine, metabolomics, and biomedical
engineering. The grounds of interpretation of Raman spectra in these cases is
the isolated macromolecules constituent vibrational assignment. Due to this,
probe the anharmonic interactions or the mutual interactions among specific
moieties/side chains to name but a few is a challenge. We present a complete
vibrational modes calculation for connective tissue in the fingerprint region
($800-1800$ cm$^{-1}$) using first-principles Density Functional Theory. Our
results indicated that important spectral features correlated to molecular
characteristics have been ignored within the usual tissue spectral bands
assignments. In particular, we found that the presence of confined water is the
main responsible for the observed spectral complexity. Our calculations
accounted for the inherent complexity of the spectral features in this region
and useful spectral markers for biological processes were unambiguously
identified.
