Dynamic enzymatic synthesis of γ-cyclodextrin using a photoremovable hydrazone template

The high water solubility of gamma-cyclodextrin (gamma-CD) lowers its synthetic yield and complicates its post-synthetic recovery, thus increasing production costs. Here, we report the use of a photoremovable hydrazone template as a proof-of-concept strategy for increasing the efficiency of the enzymatic synthesis of gamma-CD and lowering the associated production costs. Our results show that while both the Z and E isomers of the hydrazone switch form low affinity (K = 250-725 M-1) complexes with beta-CD (1:1), only the Z isomer of the switch can be included in gamma-CD (2:1; K-2 = 8,970 M-1). We used this property to preferably synthesize gamma-CD and increase its yield by 6-fold and then took advantage of the photoremovable nature of the template to isolate the product. Considering the very limited number of photoswitches that can bind to gamma-CDs, we anticipate that this newly discovered host-guest couple will open the way for designing gamma-CD-based adaptive materials.

Automated summary

The high water solubility of gamma-cyclodextrin can lower synthetic yield and increase production costs, but a photoremovable hydrazone template has been shown to increase efficiency in enzymatic synthesis and reduce costs. The Z isomer of the hydrazone switch is preferentially included in gamma-CD, leading to a 6-fold increase in yield. This discovery may pave the way for designing adaptive materials based on gamma-CD.