Glucose-induced structural changes and anomalous diffusion of elastin.

Elastin is the principal protein component of elastic fiber, which renders essential elasticity to connective tissues and organs. Here, we adopted a multi-technique approach to study the transport, viscoelastic, and structural properties of elastin exposed to various glucose concentrations (X=[gluc]/[elastin]). Laser light scattering experiments revealed an anomalous behavior (anomaly exponent, β <0.6) of elastin. In this regime (β <0.6), the diffusion constant decreases by 40% in the presence of glucose (X> 10), which suggests the structural change in elastin. We have observed a peculiar inverse temperature transition of elastin protein, which is a measure of structural change, at 40 °C through rheology experiments. Moreover, we observe its shift towards lower temperature with a higher X. FTIR revealed that the presence of glucose (X < 10) favors the formation of β-sheet structure in elastin. However, for X > 10, dominative crowding effect reduces the mobility of protein and favors the increase in β-turns and γ-turns by 25 ± 1% over the β-sheet (β-sheet decreases by 12 ± 0.8%) and α-helix (α-helix decreases by 13 ± 0.8%). The stiffness of protein is estimated through Flory characteristic ratio, C∞ and found to be increasing with X. These glucose-based structural changes in the elastin may explain the role of glucose in age-related issues of the skin.