Study on the association between CTD peptides and zinc(II)-dipicolylamine appended beta-cyclodextrin

Association between zinc(II)-dipicolylamine (ZnDpa) appended beta-cyclodextrin (beta-CD) and CTD (carboxy-terminal domain of RNA polymerase II) peptides with different phosphorylation patterns was studied by isothermal titration calorimetry (ITC) and nuclear magnetic resonance (NMR). The receptor displayed association constants of 6.52 x 10(3) to 1.49 x 10(5) towards the phosphorylated peptides, which are 16 to 72 times higher than that of ZnDpa, indicating the involvement of molecular recognition of beta-CD. NMR results confirm the involvement of beta-CD in the association, i.e. the aromatic ring on the tyrosine of the peptide was included in the cavity of CD, while the inclusion manners are different among the peptides.