Cyclodextrin and its derivatives enhance protein crystallization by grafted on crystallization plates

Protein drugs are attracting increasing attention. Eight of best-selling drugs in worldwide are proteins. Crystallization is an important protein purification method; however, it remains a bottleneck step. Heterogeneous nucleate is an effective method of enhancing protein crystallization. Cyclodextrin has been widely used in pharmaceutics, and our previous study showed that it is an effective heterogeneous nucleate for enhancing protein crystallization, and it may be widely used in purification of protein drugs. However, cyclodextrin must be added into the crystallization plate wells by hand, which is labor intensive and is not beneficial to automated crystallization screening. We grafted β-cyclodextrin (β-CD) and its derivatives (i.e., p-toluenesulfonyl-β-cyclodextrin [PTCD], mono-(6-(1,6-hexamethylenediamine)-6-deoxy)-β-cyclodextrin [MHCD] and mercapto-β-cyclodextrin [MCD]) on crystallization plates and tested their effects on protein crystallization. Protein crystallization success rate was improved, particularly for the PTCD-grafted group. This is an easy method to facilitate protein crystallization and can be widely applied for automatic crystallization screening.