[Parameters of heat disruption of native collagen structures and their connection with biological growth]

By means of differential scanning calorimetry we have studied the influence of structural changes induced by the biological aging on the processes of thermal denaturation of collagen tissue (rat tail tendon, age from 14 days to 24 months). We have found that some parameters of the thermal denaturation process, namely, the denaturation temperature Td and the denaturation heat Qd are sensitive to the biological age of the tissue. Both Td and Qd are increasing with the age. However, this increase takes place only on early stages of aging. When the denaturation heat Qd of the tissue is normalized on the content of collagen in it, one obtains the independent on the age value of 75 J/g. So the increase of Qd with aging reflects the increase of the collagen content in tissue. We have found that the half-widths of the denaturation curves delta T 1/2, as well as the heat capacity increment at denaturation delta Cp do not depend on the tissue age. Both for fibrills of collagen and for its solution the measured value of delta Cp is equal 0.42 +/- 0.004 J/g degrees C which differs considerably from the earlier published data.