Noncovalent PEGylation via Sulfonatocalix[4]arene-A Crystallographic Proof.

Noncovalent or supramolecular PEGylation, in combination with the site of administration, has great potential to increase the half-life of therapeutic proteins. To date, a variety of noncovalent PEGylation strategies have been devised. However, questions remain concerning the nature of the protein-PEG interaction.

Protein Recognition by Functionalized Sulfonatocalix[4]arenes.

The interactions of two mono-functionalized sulfonatocalix[4]arenes with cytochrome c were investigated by structural and thermodynamic methods. The replacement of a single sulfonate with either a bromo or a phenyl substituent resulted in altered recognition of cytochrome c as evidenced by X-ray crystallography. The bromo-substituted ligand yielded a new binding mode in which a self-encapsulated calixarene dimer contributed to crystal packing.

Protein Dimerization on a Phosphonated Calix[6]arene Disc.

Complex formation between cationic cytochrome c and the water-soluble, poly-anionic p-phosphonatocalix[6]arene (pclx ) was investigated. A crystal structure (at 1.8 Å resolution) revealed a remarkable dimeric disc of pclx that acts like glue to mediate a symmetric (C ) protein dimer.

Study of cytochrome c-DNA interaction--evaluation of binding sites on the redox protein.

Artificial assemblies consisting of the cationic cytochrome c (cyt c) and double-stranded DNA are interesting for the field of biohybrid systems because of the high electro-activity of the incorporated redox protein. However, little is known about the interactions between these two biomolecules. Here, the complex of reduced cyt c and a 41 base pair oligonucleotide was characterized in solution as a function of pH and ionic strength.