Executive Summary : | Protein-conjugate-based drugs constitute the most rapidly growing segment of therapeutics. Besides, the functionalization of proteins is essential for diverse biochemical and biophysical systems. However, the technological demand for methods for the precision engineering of proteins remains unmet. Rai and coworkers developed the DIN theory and initial principles for single-site modification of proteins.² However, more than 95% of the protein landscape is beyond the reach of such methods. In its early stage, the field requires new parameters and tools to access unexplored targets without compromising precision. We draw inspiration from regulated access to a membrane protein's extracellular, transmembrane, and intracellular domains within live cells. In this perspective, we propose that biomaterial matrices can play a critical role in "accessibility regulation” to enable single-site modification of proteins.³ First, we will prepare the biomaterial matrix (Figure 1) and LDMK-K reagents. subsequently, we will test them with model proteins embedded in the matrixes. The successful methods will be translated to construct antibody conjugates. In particular, antibody-fluorophore conjugate (AFC) and antibody-drug conjugate (ADC) capable of targeting HER2-positive breast cancer cells would be developed. Next, we will examine how it performs with a mixture of proteins. Finally, we will extend the method to a highly complex biological milieu derived from eukaryotic cell lysate to examine protein specificity. |