Abstract
The denaturation of collagen solution in acetic acid has been investigated by using ultraβsensitive differential scanning calorimetry (USβDSC), circular dichroism (CD), and laser light scattering (LLS). USβDSC measurements reveal that the collagen exhibits a bimodal transition, i.e., there exists a shoulder transition before the major transition. Such a shoulder transition can recover from a cooling when the collagen is heated to a temperature below 35Β°C. However, when the heating temperature is above 37Β°C, both the shoulder and major transitions are irreversible. CD measurements demonstrate the content of triple helix slowly decreases with temperature at a temperature below 35Β°C, but it drastically decreases at a higher temperature. Our experiments suggest that the shoulder transition and major transition arise from the defibrillation and denaturation of collagen, respectively. LLS measurements show the average hydrodynamic radius γR~h~γ, radius of gyration γR~g~γof the collagen gradually decrease before a sharp decrease at a higher temperature. Meanwhile, the ratio γR~g~γ/γR~h~γ gradually increases at a temperature below βΌ 34Β°C and drastically increases in the range 34β40Β°C, further indicating the defibrillation of collagen before the denaturation. Β© 2007 Wiley Periodicals, Inc. Biopolymers 86: 282β287, 2007.
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