Collagen: mobile water content of frozen fibers.

From the change in the nuclear magnetic resonance splitting of heavy water in oriented wet collagen fibers at low temperatures, it is estimated that about 0.6 gram of heavy water per gram of collagen does not freeze. This estimate has been confirmed by a measurement of the heat evolved on melting "frozen" wet collagen. The water that does not freeze retains liquid-like mobility even at temperatures as low as -50 degrees C.