Molecular conformation is considered to be an important factor in determining the biological activity of glucans, however, an easy method to detect the conformation change for glucans in solution has not been developed. We have found that the fluorescence intensity of aniline blue bound to glucan can be used to estimate the relative amount of single helix converting to triple helix during different stages of a denature-renature cycle. The native conformation for schizophyllan (SPG) (a branched -1->3 glucan) is a rigid closed triple helix. Treatment with NaOH produces a single helix-rich preparation. We observed that aniline blue does not stain native SPG, but will stain the NaOH-treated SPG. This observation suggests that aniline blue binds only to single helix forms of SPG. The activity of renatured SPG, stabilized with aniline blue at different days, was evaluated using a glucan responsive LAL assay. The activity of LAL assay was inversely correlated with the amount of triple helix formed when SPG was renatured and stabilized over time.