The effect of glycerol and 2-propanol on the molecular aggregation of collagen in solution.

The molecular aggregation of collagen solution (Col) in the presence of glycerol (Col-G) and 2-propanol (Col-P) was investigated. The transition temperature (Tm) of collagen, determined by ultra-sensitive differential scanning calorimetry, increased proportionally to the concentration of glycerol about 0.929 °C per 1M, while Tm decreased proportionally to the concentration of 2-propanol about 1.638 °C per 1M. The fluorescence spectra of collagen in solutions were detected by two-dimensional technique on the perturbation of the concentration of glycerol and 2-propanol and showed different results in Col-G and Col-P. The size of collagen aggregates in solutions was observed by dynamic light scattering. Compared with the aggregate size in Col, collagen aggregates became smaller in the presence of glycerol, whereas it grew larger in the presence of 2-propanol. Furthermore, the different extent of aggregation in Col, Col-G and Col-P influenced the self-assembly of collagen molecules under physiological conditions, and there were differences in the resulted fibril structures of Col, Col-G and Col-P after fibrillogenesis as determined by scanning electron microscopy. These results indicated that glycerol inhibited the collagen aggregates while 2-propanol promoted them in solution.