UC Berkeley

As one of the core building blocks of life, proteins play a central role in our efforts to understand, control, and engineer the natural world. Chemical modification of proteins facilitates these efforts by allowing manipulation of protein properties and creation of new materials. A variety of methods for the modification of proteins exist, and collectively these methods have enabled the synthesis of drugs, the study of biological systems, and the creation of new materials. Unfortunately the exquisite control provided by many of these methods does not extend to oligomeric proteins, which are found ubiquitously in nature. These proteins often have symmetries and structures that make them particularly appealing for use in materials science and pharmaceutical applications, yet their multivalency makes their controlled modification difficult. This thesis describes the development of a method for protein modification in which control over the number of modification sites is exerted through noncovalent interactions. This method is able to control the level of modification of both monomeric and small oligomeric proteins. Further development revealed that this method also discriminates between different modification sites, such that it could be used to site-specifically modify proteins or monitor bioconjugation reactions. Finally, the principles used in the construction of these bioconjugation strategies were applied to the recovery of enzymes from industrial reactions.