The features of infrared spectrum of bio-polymer and its theoretical investigation

Abstract

We have here an insight into the features of molecular structures of bio-polymers with α-helix structure using infrared spectrum and elucidated theoretically, its relationship with bio-functions. In this case, we analyzed first the features of molecular structure of collagen and collected further the infrared spectrum of absorption of collagen and bovine serum albumin containing α-helix conformation in 400–4000 cm-1 as well as their changes of strength of infrared absorption with varying temperatures using Fourier Transform–Infrared (FT-IR) spectrometers in the region of 15–95°C. The results show that there is a new band of 1650 cm-1 close to the amide-I band of 1666 cm-1 or 1670 cm-1 in these bio-polymers, its strength decreases exponentially with increasing temperature of the systems, which can be expressed by exp [-(0.437 + 8.987 × 10-6 T 2)], but 1666 cm-1 band increases linearly with increasing temperature. We calculated the energy spectrum of the protein molecules with α-helix conformation using the Soliton Theory of bio-energy transport, which are basically same with the experimental results measured by us. From these results and soliton theory we can conclude that the nonlinear soliton excitation, corresponding to 1650 cm-1 band and the exciton excitation, is related to 1666 cm-1 band, exists in the collagen and bovine serum albumin. In the meanwhile, these results also verified that the soliton theory of bio-energy transport along α-helix bio-polymers is appropriate to the protein molecules with α-helix conformation. Therefore, the studied results are helpful to elucidate the relationship between the molecular structure and bio-function of these bio-polymers.