Protein Frameworks with Thiacalixarene and Zinc

[Image: see text] Controlled protein assembly provides a means to generate biomaterials. Synthetic macrocycles such as the water-soluble sulfonato-calix[n]arenes are useful mediators of protein assembly. Sulfonato-thiacalix[4]arene (tsclx(4)), with its metal-binding capacity, affords the potential for simultaneous macrocycle- and metal-mediated protein assembly. Here, we describe the tsclx(4)-/Zn-directed assembly of two proteins: cationic α-helical cytochrome c (cyt c) and neutral β-propeller Ralstonia solanacearum lectin (RSL). Two co-crystal forms were obtained with cyt c, each involving multinuclear zinc sites supported by the cone conformation of tsclx(4). The tsclx(4)/Zn cluster acted as an assembly node via both lysine encapsulation and metal-mediated protein–protein contacts. In the case of RSL, tsclx(4) adopted the 1,2-alternate conformation and supported a dinuclear zinc site with concomitant encapsulation and metal-binding of two histidine side chains. These results, together with the knowledge of thiacalixarene/metal nanoclusters, suggest promising applications for thiacalixarenes in biomaterials and MOF fabrication.