Interaction between polydeoxyadenylic acid and β-glucan from Lentinus edodes

The interaction between polydeoxyadenylic acid (poly(dA)) and single chains of Lentinan (s-LNT) was investigated by circular dichroism spectra (CD), UV-Vis spectra, nano-differential scanning calorimetry (nano-DSC), dynamic light scattering (DLS), and atomic force microscopy (AFM). All the experimental results indicated that poly(dA) really interacted with s-LNT having molecular weight of 5.3 x 10(5) to form a novel composite with stiff conformation through hydrogen bonding, whereas the triple helical Lentinan (t-LNT) could not, implying that it was the single chain but not the triple helical chain interacted with poly(dA). Meanwhile, the interaction strongly depended on the concentration of s-LNT and pH. When the poly(dA) concentration was fixed at 53 mu g/ml, the interaction between poly(dA) and s-LNT increased with an increase in s-LNT concentration, then reached the maximum at similar to 60 mu g/ml, finally decreased with further increase of s-LNT concentration. This was due to self-renaturation of s-LNT into triple helix or incomplete species confirmed by nano-DSC. The poly(dA)/s-LNT complex could exist in solutions with pH 5.5-11.5, and pH 7-10 was the optimal condition for the complex, showing higher stability against pH than the positive control of poly(dA)/s-SPG. The dynamic behaviors of the complex demonstrated that the interaction between s-LNT and poly(dA) occurred rapidly, and reached stable within 3-7 h. Moreover, the thermal stability of poly(dA) was enhanced by complexation with s-LNT. The topograph of the poly(dA)/s-LNT complex was shown as rod-like stiff architecture. This work enlarges the application of LNT in the biomedical field. (C) 2012 Published by Elsevier Ltd.